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	Translation	Source string	Target string
	cnp3-ebook/principles/naming — French	Naming and addressing	Nommage et adressage
	cnp3-ebook/principles/naming — Vietnamese	Naming and addressing	Cách đặt tên và địa chỉ
	cnp3-ebook/principles/naming — Chinese (Simplified Han script)	Naming and addressing	命名和寻址
	cnp3-ebook/principles/naming — English	Naming and addressing	Naming and addressing
	cnp3-ebook/principles/naming — French	The network and the transport layers rely on addresses that are encoded as fixed size bit strings. A network layer address uniquely identifies a host. Several transport layer entities can use the service of the same network layer. For example, a reliable transport protocol and a connectionless transport protocol can coexist on the same host. In this case, the network layer multiplexes the segments produced by these two protocols. This multiplexing is usually achieved by placing in the network packet header a field that indicates which transport protocol should process the segment. Given that there are few different transport protocols, this field does not need to be long. The port numbers play a similar role in the transport layer since they enable it to multiplex data from several application processes.	Les couches réseau et transport s'appuient sur des adresses qui sont codées sous forme de chaînes de bits de taille fixe. Une adresse de la couche réseau identifie de manière unique un hôte. Plusieurs entités de la couche transport peuvent utiliser le service de la même couche réseau. Par exemple, un protocole de transport fiable et un protocole de transport sans connexion peuvent coexister sur le même hôte. Dans ce cas, la couche réseau multiplexe les segments produits par ces deux protocoles. Ce multiplexage est généralement réalisé en plaçant dans l'en-tête du paquet réseau un champ qui indique quel protocole de transport doit traiter le segment. Étant donné qu'il existe peu de protocoles de transport différents, ce champ n'a pas besoin d'être long. Les numéros de port jouent un rôle similaire dans la couche transport puisqu'ils lui permettent de multiplexer les données de plusieurs processus d'application.
	cnp3-ebook/principles/naming — Vietnamese	The network and the transport layers rely on addresses that are encoded as fixed size bit strings. A network layer address uniquely identifies a host. Several transport layer entities can use the service of the same network layer. For example, a reliable transport protocol and a connectionless transport protocol can coexist on the same host. In this case, the network layer multiplexes the segments produced by these two protocols. This multiplexing is usually achieved by placing in the network packet header a field that indicates which transport protocol should process the segment. Given that there are few different transport protocols, this field does not need to be long. The port numbers play a similar role in the transport layer since they enable it to multiplex data from several application processes.	Các tầng giao vận và tầng mạng phụ thuộc vào các địa chỉ đã được mã hoá dưới dạng chuỗi các bit có kích thước cố định. Một địa chỉ của tầng mạng là định danh duy nhất xác định một hệ chủ. Nhiều chủ thể của tầng giao vận có thể sử dụng dịch vụ của cùng một tầng mạng. Ví dụ, một giao thức giao vận an toàn và một giao thức giao vận phi kết nối có thể cùng tồn tại trên một hệ chủ. Trong trường hợp này, tầng mạng sẽ đa truyền (multiplexe) những phần được tạo ra bởi các giao thức này. Sự đa truyền này thường đạt được bằng cách đưa một trường thông tin vào phần đầu của gói tin mạng cho biết rằng giao thức giao vận nào có thể xử lý mẩu tin này. Do chỉ có một số ít các giao thức giao vận, trường thông tin này không cần thiết phải dài. Các số cổng (port number) cũng đóng một vai trò tương tự trong lớp giao vận do chúng cho phép việc đa truyền dữ liệu từ nhiều quá trình ứng dụng.
	cnp3-ebook/principles/naming — Chinese (Simplified Han script)	The network and the transport layers rely on addresses that are encoded as fixed size bit strings. A network layer address uniquely identifies a host. Several transport layer entities can use the service of the same network layer. For example, a reliable transport protocol and a connectionless transport protocol can coexist on the same host. In this case, the network layer multiplexes the segments produced by these two protocols. This multiplexing is usually achieved by placing in the network packet header a field that indicates which transport protocol should process the segment. Given that there are few different transport protocols, this field does not need to be long. The port numbers play a similar role in the transport layer since they enable it to multiplex data from several application processes.	网络层与传输层依赖于被编码成固定长度的二进制地址。一个网络层地址可以唯一的识别一台主机。多个传输层单元可以使用同一个网络层的服务。例如，一个可靠传输协议和一个无连接传输协议可以在同一台主机上共存。在这种情况下，网络层复用于这两种协议。为了实现复用，往往通过替换数据包包头的一个特定字段来标记其所使用的传输协议。鉴于只存在几个不同的传输层协议，这个字段不需要很长。端口号在传输层扮演着同样的角色，它使得多个进程可以同时传输数据。
	cnp3-ebook/principles/naming — English	The network and the transport layers rely on addresses that are encoded as fixed size bit strings. A network layer address uniquely identifies a host. Several transport layer entities can use the service of the same network layer. For example, a reliable transport protocol and a connectionless transport protocol can coexist on the same host. In this case, the network layer multiplexes the segments produced by these two protocols. This multiplexing is usually achieved by placing in the network packet header a field that indicates which transport protocol should process the segment. Given that there are few different transport protocols, this field does not need to be long. The port numbers play a similar role in the transport layer since they enable it to multiplex data from several application processes.	The network and the transport layers rely on addresses that are encoded as fixed size bit strings. A network layer address uniquely identifies a host. Several transport layer entities can use the service of the same network layer. For example, a reliable transport protocol and a connectionless transport protocol can coexist on the same host. In this case, the network layer multiplexes the segments produced by these two protocols. This multiplexing is usually achieved by placing in the network packet header a field that indicates which transport protocol should process the segment. Given that there are few different transport protocols, this field does not need to be long. The port numbers play a similar role in the transport layer since they enable it to multiplex data from several application processes.
	cnp3-ebook/principles/naming — French	While addresses are natural for the network and transport layer entities, humans prefer to use names when interacting with network services. Names can be encoded as a character string and a mapping services allows applications to map a name into the corresponding address. Using names is friendlier for humans, but it also provides a level of indirection which is very useful in many situations.	Alors que les adresses semblent intuitives pour les entités des couches réseau et transport, les humains préfèrent utiliser des noms lorsqu'ils interagissent avec les services réseau. Les noms peuvent être codés sous forme de chaîne de caractères et un service de mappage permet aux applications de faire correspondre un nom à l'adresse correspondante. L'utilisation des noms est plus conviviale pour les humains, mais elle fournit également un niveau d'indirection qui est très utile dans de nombreuses situations.
	cnp3-ebook/principles/naming — Vietnamese	While addresses are natural for the network and transport layer entities, humans prefer to use names when interacting with network services. Names can be encoded as a character string and a mapping services allows applications to map a name into the corresponding address. Using names is friendlier for humans, but it also provides a level of indirection which is very useful in many situations.	Trong khi việc sử dụng các địa chỉ cho các thực thể tầng mạng và tầng giao vận được coi là một điều tự nhiên, con người lại thích sử dụng các tên gọi khi giao tiếp với các dịch vụ mạng. Các tên gọi có thể được mã hoá bằng các kí tự chuỗi và một dịch vụ ánh xạ cho phép các ứng dụng liên kết một tên gọi đến địa chỉ tương ứng của nó. Sử dụng các tên gọi được cho là thân thiện hơn với con người, đồng thời nó cũng cung cấp một sự mất định hướng mà sự mất định hướng này lại rất hữu dụng trong nhiều tình huống.
	cnp3-ebook/principles/naming — Chinese (Simplified Han script)	While addresses are natural for the network and transport layer entities, humans prefer to use names when interacting with network services. Names can be encoded as a character string and a mapping services allows applications to map a name into the corresponding address. Using names is friendlier for humans, but it also provides a level of indirection which is very useful in many situations.	尽管网络层和传输层的实体生来就有地址，人们更愿意使用名称来访问网络设施。名称可以被编码成一个字符串，然后通过一个映射服务映射至对应的地址。对于用户来说，使用名称是更加便利的。名称同时还能作为一层中间件，可以在许多场景下发挥作用。
	cnp3-ebook/principles/naming — English	While addresses are natural for the network and transport layer entities, humans prefer to use names when interacting with network services. Names can be encoded as a character string and a mapping services allows applications to map a name into the corresponding address. Using names is friendlier for humans, but it also provides a level of indirection which is very useful in many situations.	While addresses are natural for the network and transport layer entities, humans prefer to use names when interacting with network services. Names can be encoded as a character string and a mapping services allows applications to map a name into the corresponding address. Using names is friendlier for humans, but it also provides a level of indirection which is very useful in many situations.
	cnp3-ebook/principles/naming — English	In the early days of the Internet, only a few hosts (mainly minicomputers) were connected to the network. The most popular applications were :term:`remote login` and file transfer. By 1983, there were already five hundred hosts attached to the Internet [Zakon]_. Each of these hosts were identified by a unique address. Forcing human users to remember the addresses of the hosts that they wanted to use was not user-friendly. Humans prefer to remember names, and use them when needed. Using names as aliases for addresses is a common technique in Computer Science. It simplifies the development of applications and allows the developer to ignore the low level details. For example, by using a programming language instead of writing machine code, a developer can write software without knowing whether the variables that it uses are stored in memory or inside registers.	In the early days of the Internet, only a few hosts (mainly minicomputers) were connected to the network. The most popular applications were :term:`remote login` and file transfer. By 1983, there were already five hundred hosts attached to the Internet [Zakon]_. Each of these hosts were identified by a unique address. Forcing human users to remember the addresses of the hosts that they wanted to use was not user-friendly. Humans prefer to remember names, and use them when needed. Using names as aliases for addresses is a common technique in Computer Science. It simplifies the development of applications and allows the developer to ignore the low level details. For example, by using a programming language instead of writing machine code, a developer can write software without knowing whether the variables that it uses are stored in memory or inside registers.
	cnp3-ebook/principles/naming — French	Because names are at a higher level than addresses, they allow (both in the example of programming above, and on the Internet) to treat addresses as mere technical identifiers, which can change at will. Only the names are stable.	Étant donné que les noms sont à plus haut niveau que les adresses, ils permettent (à la fois dans l'exemple de programmation au-dessus, et sur internet) de traiter les adresses comme de simples identifiants techniques qui peuvent changer à volonté. Seuls les noms restent stables.
	cnp3-ebook/principles/naming — Vietnamese	Because names are at a higher level than addresses, they allow (both in the example of programming above, and on the Internet) to treat addresses as mere technical identifiers, which can change at will. Only the names are stable.	Bởi vì các tên gọi nằm ở tầng cao hơn so với các địa chỉ, chúng cho phép (cả trong ví dụ của ngôn ngữ lập trình ở trên cũng như với mạng Internet) việc coi các địa chỉ đơn giản chỉ là các định danh kĩ thuật, mà các định danh này có thể được thay đổi theo ý muốn. Chỉ có các tên gọi là được giữ ổn định.
	cnp3-ebook/principles/naming — English	Because names are at a higher level than addresses, they allow (both in the example of programming above, and on the Internet) to treat addresses as mere technical identifiers, which can change at will. Only the names are stable.	Because names are at a higher level than addresses, they allow (both in the example of programming above, and on the Internet) to treat addresses as mere technical identifiers, which can change at will. Only the names are stable.
	cnp3-ebook/principles/naming — French	The first solution that allowed applications to use names was the :term:`hosts.txt` file. This file is similar to the symbol table found in compiled code. It contains the mapping between the name of each Internet host and its associated address [#fhosts]_. It was maintained by SRI International that coordinated the Network Information Center (NIC). When a new host was connected to the network, the system administrator had to register its name and address at the NIC. The NIC updated the :term:`hosts.txt` file on its server. All Internet hosts regularly retrieved the updated :term:`hosts.txt` file from the SRI_ server. This file was stored at a well-known location on each Internet host (see :rfc:`952`) and networked applications could use it to find the address corresponding to a name.	La première solution permettant aux applications d'utiliser des noms était le fichier :term:`hosts.txt`. Ce fichier est similaire à la table des symboles que l'on trouve dans un code compilé. Il contient la correspondance entre le nom de chaque hôte Internet et son adresse associée [#fhosts]_. Il était maintenu par SRI International qui coordonnait le Network Information Center (NIC). Lorsqu'un nouvel hôte était connecté au réseau, l'administrateur système devait enregistrer son nom et son adresse auprès du NIC. Le NIC mettait à jour le fichier :term:`hosts.txt` sur son serveur. Tous les hôtes Internet récupéraient régulièrement le fichier :term:`hosts.txt` mis à jour sur le serveur SRI_. Ce fichier était stocké à un emplacement bien connu sur chaque hôte Internet (voir :rfc:`952`) et les applications en réseau pouvaient l'utiliser pour trouver l'adresse correspondant à un nom.
	cnp3-ebook/principles/naming — Vietnamese	The first solution that allowed applications to use names was the :term:`hosts.txt` file. This file is similar to the symbol table found in compiled code. It contains the mapping between the name of each Internet host and its associated address [#fhosts]_. It was maintained by SRI International that coordinated the Network Information Center (NIC). When a new host was connected to the network, the system administrator had to register its name and address at the NIC. The NIC updated the :term:`hosts.txt` file on its server. All Internet hosts regularly retrieved the updated :term:`hosts.txt` file from the SRI_ server. This file was stored at a well-known location on each Internet host (see :rfc:`952`) and networked applications could use it to find the address corresponding to a name.	Giải pháp đầu tiên cho phép các ứng dụng sử dụng các tên gọi là tệp tin :term:`hosts.txt`. Tệp tin này giống như bảng ký tự tìm thấy ở trong các mã đã biên dịch. Nó bao gồm các ánh xạ giữa tên của mỗi một trạm Internet với địa chỉ tương ứng của nó [#fhosts]_. Nó được duy trì bởi SRI International, một đơn vị điều phối Network Information Center (NIC). Khi một trạm mới được kết nối vào mạng, người quản trị hệ thống cần đăng ký tên đó và địa chỉ tương ứng với NIC. Khi đó, NIC cập nhật tệp tin :term:`hosts.txt` trên máy chủ của họ. Tất cả các trạm Internet đều thường xuyên nhận được các tệp tin :term:`hosts.txt` cập nhật từ SRI_server. Tệp tin này được lưu tại một vị trí phổ biến trên mỗi một trạm Internet (tham khảo :rfc:`952`) và các ứng dụng kết nối mạng có thể sử dụng nó để tìm địa chỉ tương ứng với tên.
	cnp3-ebook/principles/naming — English	The first solution that allowed applications to use names was the :term:`hosts.txt` file. This file is similar to the symbol table found in compiled code. It contains the mapping between the name of each Internet host and its associated address [#fhosts]_. It was maintained by SRI International that coordinated the Network Information Center (NIC). When a new host was connected to the network, the system administrator had to register its name and address at the NIC. The NIC updated the :term:`hosts.txt` file on its server. All Internet hosts regularly retrieved the updated :term:`hosts.txt` file from the SRI_ server. This file was stored at a well-known location on each Internet host (see :rfc:`952`) and networked applications could use it to find the address corresponding to a name.	The first solution that allowed applications to use names was the :term:`hosts.txt` file. This file is similar to the symbol table found in compiled code. It contains the mapping between the name of each Internet host and its associated address [#fhosts]_. It was maintained by SRI International that coordinated the Network Information Center (NIC). When a new host was connected to the network, the system administrator had to register its name and address at the NIC. The NIC updated the :term:`hosts.txt` file on its server. All Internet hosts regularly retrieved the updated :term:`hosts.txt` file from the SRI_ server. This file was stored at a well-known location on each Internet host (see :rfc:`952`) and networked applications could use it to find the address corresponding to a name.
	cnp3-ebook/principles/naming — French	A :term:`hosts.txt` file can be used when there are up to a few hundred hosts on the network. However, it is clearly not suitable for a network containing thousands or millions of hosts. A key issue in a large network is to define a suitable naming scheme. The ARPANet initially used a flat naming space, i.e. each host was assigned a unique name. To limit collisions between names, these names usually contained the name of the institution and a suffix to identify the host inside the institution (a kind of poor man's hierarchical naming scheme). On the ARPANet few institutions had several hosts connected to the network.	Un fichier :term:`hosts.txt` peut être utilisé lorsqu'il y a jusqu'à quelques centaines d'hôtes sur le réseau. Cependant, il n'est clairement pas adapté à un réseau contenant des milliers ou des millions d'hôtes. Un problème clé dans un grand réseau est de définir un schéma de nommage approprié. L'ARPANet utilisait initialement un espace de nommage plat, c'est-à-dire que chaque hôte se voyait attribuer un nom unique. Pour limiter les collisions entre les noms, ces noms contenaient généralement le nom de l'institution et un suffixe permettant d'identifier l'hôte à l'intérieur de l'institution (une sorte de schéma de nommage hiérarchique du pauvre). Sur ARPANet, quelques institutions avaient plusieurs hôtes connectés au réseau.
	cnp3-ebook/principles/naming — Vietnamese	A :term:`hosts.txt` file can be used when there are up to a few hundred hosts on the network. However, it is clearly not suitable for a network containing thousands or millions of hosts. A key issue in a large network is to define a suitable naming scheme. The ARPANet initially used a flat naming space, i.e. each host was assigned a unique name. To limit collisions between names, these names usually contained the name of the institution and a suffix to identify the host inside the institution (a kind of poor man's hierarchical naming scheme). On the ARPANet few institutions had several hosts connected to the network.	Một tệp tin :term:`hosts.txt` có thể được sử dụng khi có khoảng vài trăm trạm trong mạng. Tuy nhiên, nó hoàn toàn không phù hợp với một mạng với hàng nghìn hoặc hàng triệu trạm. Một vấn đề chính trong một một mạng lớn đó chính là việc định nghĩa một lược đồ tên gọi phù hợp. ARPANet đầu tiên đã sử dụng một không gian tên phẳng, ví dụ như là mỗi trạm được đặt một tên duy nhất. Để tránh việc trùng lặp giữa các tên, chúng thường bao gồm tên của tổ chức và một hậu tố để xác định trạm đó bên trong tổ chức (một kiểu đặt tên theo thứ bậc nghèo nàn). Trên mạng ARPANet chỉ có một vài tổ chức với nhiều trạm kết nối với mạng.
	cnp3-ebook/principles/naming — English	A :term:`hosts.txt` file can be used when there are up to a few hundred hosts on the network. However, it is clearly not suitable for a network containing thousands or millions of hosts. A key issue in a large network is to define a suitable naming scheme. The ARPANet initially used a flat naming space, i.e. each host was assigned a unique name. To limit collisions between names, these names usually contained the name of the institution and a suffix to identify the host inside the institution (a kind of poor man's hierarchical naming scheme). On the ARPANet few institutions had several hosts connected to the network.	A :term:`hosts.txt` file can be used when there are up to a few hundred hosts on the network. However, it is clearly not suitable for a network containing thousands or millions of hosts. A key issue in a large network is to define a suitable naming scheme. The ARPANet initially used a flat naming space, i.e. each host was assigned a unique name. To limit collisions between names, these names usually contained the name of the institution and a suffix to identify the host inside the institution (a kind of poor man's hierarchical naming scheme). On the ARPANet few institutions had several hosts connected to the network.
	cnp3-ebook/principles/naming — French	However, the limitations of a flat naming scheme became clear before the end of the ARPANet and :rfc:`819` proposed a hierarchical naming scheme. While :rfc:`819` discussed the possibility of organizing the names as a directed graph, the Internet opted for a tree structure capable of containing all names. In this tree, the top-level domains are those that are directly attached to the root. The first top-level domain was `.arpa` [#fdnstimeline]_. This top-level name was initially added as a suffix to the names of the hosts attached to the ARPANet and listed in the `hosts.txt` file. In 1984, the `.gov`, `.edu`, `.com`, `.mil` and `.org` generic top-level domain names were added. :rfc:`1032` proposed the utilization of the two letter :term:`ISO-3166` country codes as top-level domain names. Since :term:`ISO-3166` defines a two letter code for each country recognized by the United Nations, this allowed all countries to automatically have a top-level domain. These domains include `.be` for Belgium, `.fr` for France, `.us` for the USA, `.ie` for Ireland or `.tv` for Tuvalu, a group of small islands in the Pacific or `.tm` for Turkmenistan. The set of top-level domain-names is managed by the Internet Corporation for Assigned Names and Numbers (:term:`ICANN`). :term:`ICANN` adds generic top-level domains that are not related to a country and the `.cat` top-level domain has been registered for the Catalan language. There are ongoing discussions within :term:`ICANN` to increase the number of top-level domains.	Cependant, les limites d'un schéma de nommage plat sont apparues clairement avant la fin de l'ARPANet et :rfc:`819` a proposé un schéma de nommage hiérarchique. Alors que la norme :rfc:`819` envisageait la possibilité d'organiser les noms sous la forme d'un graphe dirigé, Internet a opté pour une structure arborescente capable de contenir tous les noms. Dans cette arborescence, les domaines de premier niveau sont ceux qui sont directement rattachés à la racine. Le premier domaine de premier niveau était `.arpa` [#fdnstimeline]_. Ce nom de premier niveau a été initialement ajouté comme suffixe aux noms des hôtes attachés à l'ARPANet et listés dans le fichier `hosts.txt`. En 1984, les noms de domaine génériques de premier niveau `.gov`, `.edu`, `.com`, `.mil` et `.org` ont été ajoutés. La norme :rfc:`1032` proposait l'utilisation des codes pays à deux lettres :term:`ISO-3166` comme noms de domaine de premier niveau. Puisque :term:`ISO-3166` définit un code de deux lettres pour chaque pays reconnu par les Nations Unies, cela permettait à tous les pays d'avoir automatiquement un domaine de premier niveau. Ces domaines incluent `.be` pour la Belgique, `.fr` pour la France, `.us` pour les États-Unis, `.ie` pour l'Irlande ou `.tv` pour Tuvalu, un groupe de petites îles du Pacifique ou `.tm` pour le Turkménistan. L'ensemble des noms de domaine de premier niveau est géré par l'Internet Corporation for Assigned Names and Numbers (:term:`ICANN`). :term:`ICANN` ajoute des domaines de premier niveau génériques qui ne sont pas liés à un pays et le domaine de premier niveau `.cat` a été enregistré pour la langue catalane. Des discussions sont en cours au sein de :term:`ICANN` pour augmenter le nombre de domaines de premier niveau.
	cnp3-ebook/principles/naming — Vietnamese	However, the limitations of a flat naming scheme became clear before the end of the ARPANet and :rfc:`819` proposed a hierarchical naming scheme. While :rfc:`819` discussed the possibility of organizing the names as a directed graph, the Internet opted for a tree structure capable of containing all names. In this tree, the top-level domains are those that are directly attached to the root. The first top-level domain was `.arpa` [#fdnstimeline]_. This top-level name was initially added as a suffix to the names of the hosts attached to the ARPANet and listed in the `hosts.txt` file. In 1984, the `.gov`, `.edu`, `.com`, `.mil` and `.org` generic top-level domain names were added. :rfc:`1032` proposed the utilization of the two letter :term:`ISO-3166` country codes as top-level domain names. Since :term:`ISO-3166` defines a two letter code for each country recognized by the United Nations, this allowed all countries to automatically have a top-level domain. These domains include `.be` for Belgium, `.fr` for France, `.us` for the USA, `.ie` for Ireland or `.tv` for Tuvalu, a group of small islands in the Pacific or `.tm` for Turkmenistan. The set of top-level domain-names is managed by the Internet Corporation for Assigned Names and Numbers (:term:`ICANN`). :term:`ICANN` adds generic top-level domains that are not related to a country and the `.cat` top-level domain has been registered for the Catalan language. There are ongoing discussions within :term:`ICANN` to increase the number of top-level domains.	Tuy nhiên, những giới hạn của việc đặt tên phẳng trở nên rõ ràng trước khi ARPANet kết thúc và :rfc:`819` đề xuất một hình thức đặt tên có thứ bậc. Khi :rfc:`819` thảo luận về khả năng của việc tổ chức các tên gọi như là một đồ thị có hướng, thì mạng Internet đã chọn một cấu trúc cây có khả năng chứa tất cả các tên gọi. Trong cây này, những tên miền ở cấp cao nhất (top-level domains) là những tên miền trực tiếp gắn với nút gốc của cây. Tên miền cấp cao nhất đầu tiên là `.arpa` [#fdnstimeline]_. Tên miền cấp cao nhất này đầu tiên được thêm vào như là một hậu tố cho các tên gọi của các trạm gắn với ARPANet và được liệt kê trong tệp tin `hosts.txt`. Vào năm 1984, các tên miền cấp cao phổ biến như `.gov`, `.edu`, `.com`, `.mil` và `.org` đã được thêm vào. :rfc:`1032` đề xuất việc sử dụng các tên miền cao cấp là các mã đất nước bao gồm hai ký tự :term:`ISO-3166`. Khi :term:`ISO-3166` định nghĩa mã gồm hai ký tự cho mỗi một nước được ghi nhận bởi Liên hợp quốc, các quốc gia mặc nhiên có tên miền cấp cao của mỗi nước. Các tên miền này bao gồm `.be` cho Bỉ, `.fr` cho Pháp, `.us` cho Mỹ, `.ie` cho Ireland hoặc `.tv` cho Tuvalu (một đảo quốc ở Thái Bình Dương) hoặc `.tm` cho Turkmenistan. Việc định ra các tên miền cao cấp được quản lý bởi tổ chức Internet Corporation for Assigned Names and Numbers (:term:`ICANN`). :term:`ICANN` còn thêm vào các tên miền cao cấp không liên quan đến quốc gia và vì vậy tên miền cao cấp `.cat` đã được đăng ký cho ngôn ngữ Catalan. Hiện tại đang có các cuộc thảo luận tại :term:`ICANN` để tăng số lượng các tên miền cao cấp.
	cnp3-ebook/principles/naming — English	However, the limitations of a flat naming scheme became clear before the end of the ARPANet and :rfc:`819` proposed a hierarchical naming scheme. While :rfc:`819` discussed the possibility of organizing the names as a directed graph, the Internet opted for a tree structure capable of containing all names. In this tree, the top-level domains are those that are directly attached to the root. The first top-level domain was `.arpa` [#fdnstimeline]_. This top-level name was initially added as a suffix to the names of the hosts attached to the ARPANet and listed in the `hosts.txt` file. In 1984, the `.gov`, `.edu`, `.com`, `.mil` and `.org` generic top-level domain names were added. :rfc:`1032` proposed the utilization of the two letter :term:`ISO-3166` country codes as top-level domain names. Since :term:`ISO-3166` defines a two letter code for each country recognized by the United Nations, this allowed all countries to automatically have a top-level domain. These domains include `.be` for Belgium, `.fr` for France, `.us` for the USA, `.ie` for Ireland or `.tv` for Tuvalu, a group of small islands in the Pacific or `.tm` for Turkmenistan. The set of top-level domain-names is managed by the Internet Corporation for Assigned Names and Numbers (:term:`ICANN`). :term:`ICANN` adds generic top-level domains that are not related to a country and the `.cat` top-level domain has been registered for the Catalan language. There are ongoing discussions within :term:`ICANN` to increase the number of top-level domains.	However, the limitations of a flat naming scheme became clear before the end of the ARPANet and :rfc:`819` proposed a hierarchical naming scheme. While :rfc:`819` discussed the possibility of organizing the names as a directed graph, the Internet opted for a tree structure capable of containing all names. In this tree, the top-level domains are those that are directly attached to the root. The first top-level domain was `.arpa` [#fdnstimeline]_. This top-level name was initially added as a suffix to the names of the hosts attached to the ARPANet and listed in the `hosts.txt` file. In 1984, the `.gov`, `.edu`, `.com`, `.mil` and `.org` generic top-level domain names were added. :rfc:`1032` proposed the utilization of the two letter :term:`ISO-3166` country codes as top-level domain names. Since :term:`ISO-3166` defines a two letter code for each country recognized by the United Nations, this allowed all countries to automatically have a top-level domain. These domains include `.be` for Belgium, `.fr` for France, `.us` for the USA, `.ie` for Ireland or `.tv` for Tuvalu, a group of small islands in the Pacific or `.tm` for Turkmenistan. The set of top-level domain-names is managed by the Internet Corporation for Assigned Names and Numbers (:term:`ICANN`). :term:`ICANN` adds generic top-level domains that are not related to a country and the `.cat` top-level domain has been registered for the Catalan language. There are ongoing discussions within :term:`ICANN` to increase the number of top-level domains.
	cnp3-ebook/principles/naming — French	Each top-level domain is managed by an organization that decides how sub-domain names can be registered. Most top-level domain names use a first-come first served system, and allow anyone to register domain names, but there are some exceptions. For example, `.gov` is reserved for the US government, `.int` is reserved for international organizations and names in the `.ca` are mainly `reserved <http://en.wikipedia.org/wiki/.ca>`_ for companies or users that are present in Canada.	Chaque domaine de premier niveau est géré par une organisation qui décide comment les noms de sous-domaines peuvent être enregistrés. La plupart des noms de domaine de premier niveau utilisent un système de premier arrivé, premier servi, et permettent à quiconque d'enregistrer des noms de domaine, mais il existe quelques exceptions. Par exemple, `.gov` est réservé au gouvernement américain, `.int` est réservé aux organisations internationales et les noms dans le `.ca` sont principalement `réservés <http://en.wikipedia.org/wiki/.ca>`_ aux entreprises ou aux utilisateurs qui sont présents au Canada.
	cnp3-ebook/principles/naming — Vietnamese	Each top-level domain is managed by an organization that decides how sub-domain names can be registered. Most top-level domain names use a first-come first served system, and allow anyone to register domain names, but there are some exceptions. For example, `.gov` is reserved for the US government, `.int` is reserved for international organizations and names in the `.ca` are mainly `reserved <http://en.wikipedia.org/wiki/.ca>`_ for companies or users that are present in Canada.	Mỗi một tên miền cao cấp được quản lý bởi một tổ chức quyết định việc làm thế nào các tên miền thứ cấp được đăng ký. Phần lớn các tên miền cao cấp sử dụng hệ thống "first-come first served" (ai đến trước thì phục vụ trước), và cho phép bất kỳ ai cũng có thể đăng ký các tên miền với một số ngoại lệ. Ví dụ, `.gov` được bảo lưu cho chính phủ Mỹ, `.int` được bảo lưu cho các tổ chức quốc tế và các tên `.ca` (`reserved <http://en.wikipedia.org/wiki/.ca>`_) chủ yếu được bảo lưu cho các công ty hoặc người dùng ở Canada.
	cnp3-ebook/principles/naming — English	Each top-level domain is managed by an organization that decides how sub-domain names can be registered. Most top-level domain names use a first-come first served system, and allow anyone to register domain names, but there are some exceptions. For example, `.gov` is reserved for the US government, `.int` is reserved for international organizations and names in the `.ca` are mainly `reserved <http://en.wikipedia.org/wiki/.ca>`_ for companies or users that are present in Canada.	Each top-level domain is managed by an organization that decides how sub-domain names can be registered. Most top-level domain names use a first-come first served system, and allow anyone to register domain names, but there are some exceptions. For example, `.gov` is reserved for the US government, `.int` is reserved for international organizations and names in the `.ca` are mainly `reserved <http://en.wikipedia.org/wiki/.ca>`_ for companies or users that are present in Canada.
	cnp3-ebook/principles/naming — French	The syntax of the domain names has been defined more precisely in :rfc:`1035`. This document recommends the following :term:`BNF` for fully qualified domain names (the domain names themselves have a much richer syntax).	La syntaxe des noms de domaine a été définie plus précisément dans :rfc:`1035`. Ce document recommande la :term:`BNF` suivante pour les noms de domaine pleinement qualifiés (les noms de domaine eux-mêmes ont une syntaxe beaucoup plus riche).
	cnp3-ebook/principles/naming — Vietnamese	The syntax of the domain names has been defined more precisely in :rfc:`1035`. This document recommends the following :term:`BNF` for fully qualified domain names (the domain names themselves have a much richer syntax).	Cú pháp của các tên miền được định nghĩa cụ thể hơn tại :rfc:`1035`. Tài liệu này gợi ý định dạng :term:`BNF` (Backus-Naur form) cho các tên miền đủ điều kiện (bản thân các tên miền có các cú pháp phong phú hơn nhiều).
	cnp3-ebook/principles/naming — English	The syntax of the domain names has been defined more precisely in :rfc:`1035`. This document recommends the following :term:`BNF` for fully qualified domain names (the domain names themselves have a much richer syntax).	The syntax of the domain names has been defined more precisely in :rfc:`1035`. This document recommends the following :term:`BNF` for fully qualified domain names (the domain names themselves have a much richer syntax).
	cnp3-ebook/principles/naming — French	BNF of the fully qualified host names	BNF du nom d'hôte pleinement qualifié
	cnp3-ebook/principles/naming — Vietnamese	BNF of the fully qualified host names	BNF của một tên trạm đầy đủ
	cnp3-ebook/principles/naming — English	BNF of the fully qualified host names	BNF of the fully qualified host names
	cnp3-ebook/principles/naming — French	This grammar specifies that a host name is an ordered list of labels separated by the dot (`.`) character. Each label can contain letters, numbers and the hyphen character (`-`) [#fidn]_. Fully qualified domain names are read from left to right. The first label is a hostname or a domain name followed by the hierarchy of domains and ending with the root implicitly at the right. The top-level domain name must be one of the registered TLDs [#ftld]_. For example, in the above figure, `www.computer-networking.info` corresponds to a host named `www` inside the `computer-networking` domain that belongs to the `info` top-level domain.	Cette grammaire spécifie qu'un nom d'hôte est une liste ordonnée d'étiquettes séparées par le caractère point (`.`). Chaque étiquette peut contenir des lettres, des chiffres et le caractère tiret (`-`) [#fidn]_. Les noms de domaine entièrement qualifiés sont lus de gauche à droite. Le premier label est un nom d'hôte ou un nom de domaine, suivi de la hiérarchie des domaines et se terminant par la racine implicitement à droite. Le nom de domaine de premier niveau doit être l'un des TLD enregistrés [#ftld]_. Par exemple, dans la figure ci-dessus, `www.computer-networking.info` correspond à un hôte nommé `www` dans le domaine `computer-networking` qui appartient au domaine de premier niveau `info`.
	cnp3-ebook/principles/naming — Vietnamese	This grammar specifies that a host name is an ordered list of labels separated by the dot (`.`) character. Each label can contain letters, numbers and the hyphen character (`-`) [#fidn]_. Fully qualified domain names are read from left to right. The first label is a hostname or a domain name followed by the hierarchy of domains and ending with the root implicitly at the right. The top-level domain name must be one of the registered TLDs [#ftld]_. For example, in the above figure, `www.computer-networking.info` corresponds to a host named `www` inside the `computer-networking` domain that belongs to the `info` top-level domain.	Ngữ pháp này chỉ định rõ rằng tên của một trạm là một danh sách sắp xếp của các nhãn được phân biệt bởi dấu chấm (`.`). Mỗi một nhãn có thể chứa các ký tự, số và gạch ngang (`-`) [#fidn]_. Một tên miền đầy đủ được đọc từ trái sang phải. Nhãn đầu tiên là tên máy chủ hoặc tên miền theo sau bởi thứ bậc của các tên miền và kết thúc với một gốc ở bên phải. Các tên miền cao cấp phải là tên miền đã được đăng ký TLDs [#ftld]_. Ví dụ, trong hình ở trên, `www.computer-networking.info` tương ứng với một trạm tên `www` nằm trong tên miền `computer-networking` mà tên miền này thuộc về tên miền cao cấp `info`.
	cnp3-ebook/principles/naming — English	This grammar specifies that a host name is an ordered list of labels separated by the dot (`.`) character. Each label can contain letters, numbers and the hyphen character (`-`) [#fidn]_. Fully qualified domain names are read from left to right. The first label is a hostname or a domain name followed by the hierarchy of domains and ending with the root implicitly at the right. The top-level domain name must be one of the registered TLDs [#ftld]_. For example, in the above figure, `www.computer-networking.info` corresponds to a host named `www` inside the `computer-networking` domain that belongs to the `info` top-level domain.	This grammar specifies that a host name is an ordered list of labels separated by the dot (`.`) character. Each label can contain letters, numbers and the hyphen character (`-`) [#fidn]_. Fully qualified domain names are read from left to right. The first label is a hostname or a domain name followed by the hierarchy of domains and ending with the root implicitly at the right. The top-level domain name must be one of the registered TLDs [#ftld]_. For example, in the above figure, `www.computer-networking.info` corresponds to a host named `www` inside the `computer-networking` domain that belongs to the `info` top-level domain.
	cnp3-ebook/principles/naming — French	Some visually similar characters have different character codes	Il existe des caractères similaires visuellement qui ont des character codes différents
	cnp3-ebook/principles/naming — Vietnamese	Some visually similar characters have different character codes	Một số ký tự tương tự có những mã ký tự khác nhau
	cnp3-ebook/principles/naming — English	Some visually similar characters have different character codes	Some visually similar characters have different character codes
	cnp3-ebook/principles/naming — French	The Domain Name System was created at a time when the Internet was mainly used in North America. The initial design assumed that all domain names would be composed of letters and digits :rfc:`1035`. As Internet usage grew in other parts of the world, it became important to support non-ASCII characters. For this, extensions have been proposed to the Domain Name System :rfc:`3490`. In a nutshell, the solution that is used to support Internationalized Domain Names works as follows. First, it is possible to use most of the Unicode characters to encode domain names and hostnames, with a few exceptions (for example, the dot character cannot be part of a name since it is used as a separator). Once a domain name has been encoded as a series of Unicode characters, it is then converted into a string that contains the ``xn--`` prefix and a sequence of ASCII characters. More details on these algorithms can be found in :rfc:`3490` and :rfc:`3492`.	Le système de noms de domaine a été créé à une époque où Internet était principalement utilisé en Amérique du Nord. La conception initiale supposait que tous les noms de domaine seraient composés de lettres et de chiffres :rfc:`1035`. Lorsque l'utilisation d'Internet s'est développée dans d'autres parties du monde, il est devenu important de prendre en charge les caractères non ASCII. Pour cela, des extensions ont été proposées au système de noms de domaine :rfc:`3490`. En résumé, la solution utilisée pour prendre en charge les noms de domaine internationalisés fonctionne comme suit. Tout d'abord, il est possible d'utiliser la plupart des caractères Unicode pour coder les noms de domaine et les noms d'hôte, à quelques exceptions près (par exemple, le caractère point ne peut pas faire partie d'un nom puisqu'il est utilisé comme séparateur). Une fois qu'un nom de domaine a été encodé comme une série de caractères Unicode, il est ensuite converti en une chaîne de caractères qui contient le préfixe ``xn--`` et une séquence de caractères ASCII. Vous trouverez plus de détails sur ces algorithmes dans :rfc:`3490` et :rfc:`3492`.
	cnp3-ebook/principles/naming — Vietnamese	The Domain Name System was created at a time when the Internet was mainly used in North America. The initial design assumed that all domain names would be composed of letters and digits :rfc:`1035`. As Internet usage grew in other parts of the world, it became important to support non-ASCII characters. For this, extensions have been proposed to the Domain Name System :rfc:`3490`. In a nutshell, the solution that is used to support Internationalized Domain Names works as follows. First, it is possible to use most of the Unicode characters to encode domain names and hostnames, with a few exceptions (for example, the dot character cannot be part of a name since it is used as a separator). Once a domain name has been encoded as a series of Unicode characters, it is then converted into a string that contains the ``xn--`` prefix and a sequence of ASCII characters. More details on these algorithms can be found in :rfc:`3490` and :rfc:`3492`.	Hệ thống tên miền được tạo ra vào thời điểm khi mà mạng Internet được sử dụng phần lớn ở Bắc Mỹ. Thiết kế ban đầu giả định rằng tất cả các tên miền sẽ được cấu thành từ các ký tự và chữ số :rfc:`1035`. Khi việc sử dụng Internet phát triển hơn ở các phần khác của thế giới, việc hỗ trợ các ký tự non-ASCII trở nên quan trọng. Để làm được điều đó, các phần mở rộng đã được đề xuất lên hệ thống quản lý tên miền :rfc:`3490`. Nói ngắn gọn, giải pháp được sử dụng để hỗ trợ các tên miền quốc tế được diễn đạt như sau. Đầu tiên, nó hoàn toàn khả dĩ khi sử dụng các ký tự Unicode để mã hoá các tên miền và tên trạm, với một số ngoại lệ (ví dụ, ký tự dấu chấm không thể là một phần của tên gọi vì nó được sử dụng như là một dải phân cách). Một khi một tên miền đã được mã hoá dưới dạng một chuỗi các ký tự Unicode, nó sẽ được chuyển thành một chuỗi bao gồm các tiền tố ``xn--`` và một chuỗi các ký tự ASCII. Chi tiết hơn về các thuật toán này có thể được tìm thấy tại :rfc:`3490` và :rfc:`3492`.
	cnp3-ebook/principles/naming — English	The Domain Name System was created at a time when the Internet was mainly used in North America. The initial design assumed that all domain names would be composed of letters and digits :rfc:`1035`. As Internet usage grew in other parts of the world, it became important to support non-ASCII characters. For this, extensions have been proposed to the Domain Name System :rfc:`3490`. In a nutshell, the solution that is used to support Internationalized Domain Names works as follows. First, it is possible to use most of the Unicode characters to encode domain names and hostnames, with a few exceptions (for example, the dot character cannot be part of a name since it is used as a separator). Once a domain name has been encoded as a series of Unicode characters, it is then converted into a string that contains the ``xn--`` prefix and a sequence of ASCII characters. More details on these algorithms can be found in :rfc:`3490` and :rfc:`3492`.	The Domain Name System was created at a time when the Internet was mainly used in North America. The initial design assumed that all domain names would be composed of letters and digits :rfc:`1035`. As Internet usage grew in other parts of the world, it became important to support non-ASCII characters. For this, extensions have been proposed to the Domain Name System :rfc:`3490`. In a nutshell, the solution that is used to support Internationalized Domain Names works as follows. First, it is possible to use most of the Unicode characters to encode domain names and hostnames, with a few exceptions (for example, the dot character cannot be part of a name since it is used as a separator). Once a domain name has been encoded as a series of Unicode characters, it is then converted into a string that contains the ``xn--`` prefix and a sequence of ASCII characters. More details on these algorithms can be found in :rfc:`3490` and :rfc:`3492`.
	cnp3-ebook/principles/naming — English	The possibility of using all Unicode characters to create domain names opened a new form of attack called the `homograph attack <https://en.wikipedia.org/wiki/IDN_homograph_attack>`_. This attack occurs when two character strings or domain names are visually similar but do not correspond to the same server. A simple example is https://G00GLE.COM and https://GOOGLE.COM. These two URLs are visually close but they correspond to different names (the first one does not point to a valid server [#fg00gle]_). With other Unicode characters, it is possible to construct domain names are visually equivalent to existing ones. See [Zhe2017]_ for additional details on this attack.	The possibility of using all Unicode characters to create domain names opened a new form of attack called the `homograph attack <https://en.wikipedia.org/wiki/IDN_homograph_attack>`_. This attack occurs when two character strings or domain names are visually similar but do not correspond to the same server. A simple example is https://G00GLE.COM and https://GOOGLE.COM. These two URLs are visually close but they correspond to different names (the first one does not point to a valid server [#fg00gle]_). With other Unicode characters, it is possible to construct domain names are visually equivalent to existing ones. See [Zhe2017]_ for additional details on this attack.
	cnp3-ebook/principles/naming — French	This hierarchical naming scheme is a key component of the Domain Name System (DNS). The DNS is a distributed database that contains mappings between fully qualified domain names and addresses. The DNS uses the client-server model. The clients are hosts or applications that need to retrieve the mapping for a given name. Each :term:`nameserver` stores part of the distributed database and answers the queries sent by clients. There is at least one :term:`nameserver` that is responsible for each domain. In the figure below, domains are represented by circles and there are three hosts inside domain `dom` (`h1`, `h2` and `h3`) and three hosts inside domain `a.sdom1.dom`. As shown in the figure below, a sub-domain may contain both host names and sub-domains.	Ce système de dénomination hiérarchique est un élément clé du système de noms de domaine (DNS). Le DNS est une base de données distribuée qui contient les correspondances entre les noms de domaine entièrement qualifiés et les adresses. Le DNS utilise le modèle client-serveur. Les clients sont des hôtes ou des applications qui doivent récupérer la correspondance pour un nom donné. Chaque :term:`nameserver` stocke une partie de la base de données distribuée et répond aux requêtes envoyées par les clients. Il y a au moins un :term:`nameserver` qui est responsable de chaque domaine. Dans la figure ci-dessous, les domaines sont représentés par des cercles et il y a trois hôtes dans le domaine `dom` (`h1`, `h2` et `h3`) et trois hôtes dans le domaine `a.sdom1.dom`. Comme le montre la figure ci-dessous, un sous-domaine peut contenir à la fois des noms d'hôtes et des sous-domaines.
	cnp3-ebook/principles/naming — English	This hierarchical naming scheme is a key component of the Domain Name System (DNS). The DNS is a distributed database that contains mappings between fully qualified domain names and addresses. The DNS uses the client-server model. The clients are hosts or applications that need to retrieve the mapping for a given name. Each :term:`nameserver` stores part of the distributed database and answers the queries sent by clients. There is at least one :term:`nameserver` that is responsible for each domain. In the figure below, domains are represented by circles and there are three hosts inside domain `dom` (`h1`, `h2` and `h3`) and three hosts inside domain `a.sdom1.dom`. As shown in the figure below, a sub-domain may contain both host names and sub-domains.	This hierarchical naming scheme is a key component of the Domain Name System (DNS). The DNS is a distributed database that contains mappings between fully qualified domain names and addresses. The DNS uses the client-server model. The clients are hosts or applications that need to retrieve the mapping for a given name. Each :term:`nameserver` stores part of the distributed database and answers the queries sent by clients. There is at least one :term:`nameserver` that is responsible for each domain. In the figure below, domains are represented by circles and there are three hosts inside domain `dom` (`h1`, `h2` and `h3`) and three hosts inside domain `a.sdom1.dom`. As shown in the figure below, a sub-domain may contain both host names and sub-domains.
	cnp3-ebook/principles/naming — French	A :term:`nameserver` that is responsible for domain `dom` can directly answer the following queries :	Un :term:`nameserver` qui est responsable du domaine `dom` peut directement répondre aux requêtes suivantes :
	cnp3-ebook/principles/naming — English	A :term:`nameserver` that is responsible for domain `dom` can directly answer the following queries :	A :term:`nameserver` that is responsible for domain `dom` can directly answer the following queries :
	cnp3-ebook/principles/naming — French	the address of any host residing directly inside domain `dom` (e.g. `h2.dom` in the figure above)	l'adresse de tout hôte résidant directement dans le domaine `dom` (par exemple `h2.dom` dans la figure ci-dessus)
	cnp3-ebook/principles/naming — English	the address of any host residing directly inside domain `dom` (e.g. `h2.dom` in the figure above)	the address of any host residing directly inside domain `dom` (e.g. `h2.dom` in the figure above)
	cnp3-ebook/principles/naming — French	the nameserver(s) that are responsible for any direct sub-domain of domain `dom` (i.e. `sdom1.dom` and `sdom2.dom` in the figure above, but not `z.sdom1.dom`)	le ou les serveurs de noms qui sont responsables de tout sous-domaine direct du domaine `dom` (c'est-à-dire `sdom1.dom` et `sdom2.dom` dans la figure ci-dessus, mais pas `z.sdom1.dom`)
	cnp3-ebook/principles/naming — English	the nameserver(s) that are responsible for any direct sub-domain of domain `dom` (i.e. `sdom1.dom` and `sdom2.dom` in the figure above, but not `z.sdom1.dom`)	the nameserver(s) that are responsible for any direct sub-domain of domain `dom` (i.e. `sdom1.dom` and `sdom2.dom` in the figure above, but not `z.sdom1.dom`)
	cnp3-ebook/principles/naming — French	To retrieve the mapping for host `h2.dom`, a client sends its query to the name server that is responsible for domain `.dom`. The name server directly answers the query. To retrieve a mapping for `h3.a.sdom1.dom` a DNS client first sends a query to the name server that is responsible for the `.dom` domain. This nameserver returns the nameserver that is responsible for the `sdom1.dom` domain. This nameserver can now be contacted to obtain the nameserver that is responsible for the `a.sdom1.dom` domain. This nameserver can be contacted to retrieve the mapping for the `h3.a.sdom1.dom` name. Thanks to this structure, it is possible for a DNS client to obtain the mapping of any host inside the `.dom` domain or any of its subdomains. To ensure that any DNS client will be able to resolve any fully qualified domain name, there are special nameservers that are responsible for the root of the domain name hierarchy. These nameservers are called :term:`root nameserver`.	Pour récupérer le mappage de l'hôte `h2.dom`, un client envoie sa requête au nameserver qui est responsable du domaine `.dom`. Le nameserver répond directement à la requête. Pour récupérer un mappage pour `h3.a.sdom1.dom`, un client DNS envoie d'abord une requête au nameserver qui est responsable du domaine `.dom`. Ce nameserver renvoie le nameserver responsable du domaine `sdom1.dom`. Ce nameserver peut maintenant être contacté pour obtenir le nameserver responsable du domaine `a.sdom1.dom`. Ce nameserver peut être contacté pour récupérer le mapping du nom `h3.a.sdom1.dom`. Grâce à cette structure, il est possible pour un client DNS d'obtenir le mappage de n'importe quel hôte à l'intérieur du domaine `.dom` ou de l'un de ses sous-domaines. Pour garantir que tout client DNS sera en mesure de résoudre tout nom de domaine pleinement qualifié, il existe des nameservers spéciaux qui sont responsables de la racine de la hiérarchie des noms de domaine. Ces nameservers sont appelés :term:`root nameserver`.
	cnp3-ebook/principles/naming — English	To retrieve the mapping for host `h2.dom`, a client sends its query to the name server that is responsible for domain `.dom`. The name server directly answers the query. To retrieve a mapping for `h3.a.sdom1.dom` a DNS client first sends a query to the name server that is responsible for the `.dom` domain. This nameserver returns the nameserver that is responsible for the `sdom1.dom` domain. This nameserver can now be contacted to obtain the nameserver that is responsible for the `a.sdom1.dom` domain. This nameserver can be contacted to retrieve the mapping for the `h3.a.sdom1.dom` name. Thanks to this structure, it is possible for a DNS client to obtain the mapping of any host inside the `.dom` domain or any of its subdomains. To ensure that any DNS client will be able to resolve any fully qualified domain name, there are special nameservers that are responsible for the root of the domain name hierarchy. These nameservers are called :term:`root nameserver`.	To retrieve the mapping for host `h2.dom`, a client sends its query to the name server that is responsible for domain `.dom`. The name server directly answers the query. To retrieve a mapping for `h3.a.sdom1.dom` a DNS client first sends a query to the name server that is responsible for the `.dom` domain. This nameserver returns the nameserver that is responsible for the `sdom1.dom` domain. This nameserver can now be contacted to obtain the nameserver that is responsible for the `a.sdom1.dom` domain. This nameserver can be contacted to retrieve the mapping for the `h3.a.sdom1.dom` name. Thanks to this structure, it is possible for a DNS client to obtain the mapping of any host inside the `.dom` domain or any of its subdomains. To ensure that any DNS client will be able to resolve any fully qualified domain name, there are special nameservers that are responsible for the root of the domain name hierarchy. These nameservers are called :term:`root nameserver`.
	cnp3-ebook/principles/naming — French	Each root nameserver maintains the list [#froot]_ of all the nameservers that are responsible for each of the top-level domain names and their addresses [#frootv6]_. All root nameservers cooperate and provide the same answers. By querying any of the root nameservers, a DNS client can obtain the nameserver that is responsible for any top-level-domain name. From this nameserver, it is possible to resolve any domain name.	Chaque root nameserver maintient la liste [#froot]_ de tous les nameservers qui sont responsables de chacun des noms de domaine de premier niveau et de leurs adresses [#frootv6]_. Tous les root nameservers coopèrent et fournissent les mêmes réponses. En interrogeant l'un des root nameserver, un client DNS peut obtenir le nameserver responsable de n'importe quel nom de domaine de premier niveau. À partir de ce nameserver, il est possible de résoudre n'importe quel nom de domaine.
	cnp3-ebook/principles/naming — English	Each root nameserver maintains the list [#froot]_ of all the nameservers that are responsible for each of the top-level domain names and their addresses [#frootv6]_. All root nameservers cooperate and provide the same answers. By querying any of the root nameservers, a DNS client can obtain the nameserver that is responsible for any top-level-domain name. From this nameserver, it is possible to resolve any domain name.	Each root nameserver maintains the list [#froot]_ of all the nameservers that are responsible for each of the top-level domain names and their addresses [#frootv6]_. All root nameservers cooperate and provide the same answers. By querying any of the root nameservers, a DNS client can obtain the nameserver that is responsible for any top-level-domain name. From this nameserver, it is possible to resolve any domain name.
	cnp3-ebook/principles/naming — French	To be able to contact the root nameservers, each DNS client must know their addresses. This implies, that DNS clients must maintain an up-to-date list of the addresses of the root nameservers. Without this list, it is impossible to contact the root nameservers. Forcing all Internet hosts to maintain the most recent version of this list would be difficult from an operational point of view. To solve this problem, the designers of the DNS introduced a special type of DNS server : the DNS resolvers. A :term:`resolver` is a server that provides the name resolution service for a set of clients. A network usually contains a few resolvers. Each host in these networks is configured to send all its DNS queries via one of its local resolvers. These queries are called `recursive queries` as the :term:`resolver` must recursively send requests through the hierarchy of nameservers to obtain the `answer`.	Pour pouvoir contacter les root nameserver, chaque client DNS doit connaître leurs adresses. Cela implique que les clients DNS doivent maintenir une liste à jour des adresses des root nameserver. Sans cette liste, il est impossible de contacter les root nameserver. Forcer tous les hôtes Internet à maintenir la version la plus récente de cette liste serait difficile d'un point de vue opérationnel. Pour résoudre ce problème, les concepteurs du DNS ont introduit un type spécial de serveur DNS : les résolveurs DNS. Un :term:`résolveur` est un serveur qui fournit le service de résolution de noms pour un ensemble de clients. Un réseau contient généralement quelques résolveurs. Chaque hôte de ces réseaux est configuré pour envoyer toutes ses requêtes DNS via l'un de ses résolveurs locaux. Ces requêtes sont appelées "requêtes récursives" car le :term:`resolver` doit envoyer des requêtes de manière récursive à travers la hiérarchie des nameservers pour obtenir la "réponse".
	cnp3-ebook/principles/naming — English	To be able to contact the root nameservers, each DNS client must know their addresses. This implies, that DNS clients must maintain an up-to-date list of the addresses of the root nameservers. Without this list, it is impossible to contact the root nameservers. Forcing all Internet hosts to maintain the most recent version of this list would be difficult from an operational point of view. To solve this problem, the designers of the DNS introduced a special type of DNS server : the DNS resolvers. A :term:`resolver` is a server that provides the name resolution service for a set of clients. A network usually contains a few resolvers. Each host in these networks is configured to send all its DNS queries via one of its local resolvers. These queries are called `recursive queries` as the :term:`resolver` must recursively send requests through the hierarchy of nameservers to obtain the `answer`.	To be able to contact the root nameservers, each DNS client must know their addresses. This implies, that DNS clients must maintain an up-to-date list of the addresses of the root nameservers. Without this list, it is impossible to contact the root nameservers. Forcing all Internet hosts to maintain the most recent version of this list would be difficult from an operational point of view. To solve this problem, the designers of the DNS introduced a special type of DNS server : the DNS resolvers. A :term:`resolver` is a server that provides the name resolution service for a set of clients. A network usually contains a few resolvers. Each host in these networks is configured to send all its DNS queries via one of its local resolvers. These queries are called `recursive queries` as the :term:`resolver` must recursively send requests through the hierarchy of nameservers to obtain the `answer`.
	cnp3-ebook/principles/naming — French	DNS resolvers have several advantages over letting each Internet host query directly nameservers. Firstly, regular Internet hosts do not need to maintain the up-to-date list of the addresses of the root servers. Secondly, regular Internet hosts do not need to send queries to nameservers all over the Internet. Furthermore, as a DNS resolver serves a large number of hosts, it can cache the received answers. This allows the resolver to quickly return answers for popular DNS queries and reduces the load on all DNS servers [JSBM2002]_.	Les résolveurs DNS présentent plusieurs avantages par rapport au fait de laisser chaque hôte Internet interroger directement les nameservers. Premièrement, les hôtes Internet ordinaires n'ont pas besoin de maintenir à jour la liste des adresses des root servers. Deuxièmement, les hôtes Internet ordinaires n'ont pas besoin d'envoyer des requêtes aux nameservers sur tout l'Internet. Enfin, comme un résolveur DNS dessert un grand nombre d'hôtes, il peut mettre en cache les réponses reçues. Cela permet au résolveur de renvoyer rapidement les réponses aux requêtes DNS populaires et de réduire la charge sur tous les serveurs DNS [JSBM2002]_.
	cnp3-ebook/principles/naming — English	DNS resolvers have several advantages over letting each Internet host query directly nameservers. Firstly, regular Internet hosts do not need to maintain the up-to-date list of the addresses of the root servers. Secondly, regular Internet hosts do not need to send queries to nameservers all over the Internet. Furthermore, as a DNS resolver serves a large number of hosts, it can cache the received answers. This allows the resolver to quickly return answers for popular DNS queries and reduces the load on all DNS servers [JSBM2002]_.	DNS resolvers have several advantages over letting each Internet host query directly nameservers. Firstly, regular Internet hosts do not need to maintain the up-to-date list of the addresses of the root servers. Secondly, regular Internet hosts do not need to send queries to nameservers all over the Internet. Furthermore, as a DNS resolver serves a large number of hosts, it can cache the received answers. This allows the resolver to quickly return answers for popular DNS queries and reduces the load on all DNS servers [JSBM2002]_.
	cnp3-ebook/principles/naming — French	Benefits of names	Avantages d'utiliser des noms
	cnp3-ebook/principles/naming — English	Benefits of names	Benefits of names
	cnp3-ebook/principles/naming — English	In addition to being more human friendly, using names instead of addresses inside applications has several important benefits. To understand them, let us consider a popular application that provides information stored on servers. This application involves clients and servers. The server provides information upon requests from client processes. A first deployment of this application would be to rely only on addresses. In this case, the server process would be installed on one host and the clients would connect to this server to retrieve information. Such a deployment has several drawbacks :	In addition to being more human friendly, using names instead of addresses inside applications has several important benefits. To understand them, let us consider a popular application that provides information stored on servers. This application involves clients and servers. The server provides information upon requests from client processes. A first deployment of this application would be to rely only on addresses. In this case, the server process would be installed on one host and the clients would connect to this server to retrieve information. Such a deployment has several drawbacks :
	cnp3-ebook/principles/naming — French	if the server process moves to another physical server, all clients must be informed about the new server address	si le processus serveur est déplacé vers un autre serveur physique, tous les clients doivent être informés de la nouvelle adresse du serveur
	cnp3-ebook/principles/naming — English	if the server process moves to another physical server, all clients must be informed about the new server address	if the server process moves to another physical server, all clients must be informed about the new server address
	cnp3-ebook/principles/naming — French	if there are many concurrent clients, the load of the server will increase without any possibility of adding another server without changing the server addresses used by the clients	s'il y a beaucoup de clients simultanés, la charge du serveur augmentera sans qu'il soit possible d'ajouter un autre serveur sans changer les adresses de serveur utilisées par les clients
	cnp3-ebook/principles/naming — English	if there are many concurrent clients, the load of the server will increase without any possibility of adding another server without changing the server addresses used by the clients	if there are many concurrent clients, the load of the server will increase without any possibility of adding another server without changing the server addresses used by the clients
	cnp3-ebook/principles/naming — English	Using names solves these problems and provides additional benefits. If the clients are configured with the name of the server, they will query the name service before contacting the server. The name service will resolve the name into the corresponding address. If a server process needs to move from one physical server to another, it suffices to update the name to address mapping on the name service to allow all clients to connect to the new server. The name service also enables the servers to better sustain the load. Assume a very popular server which is accessed by millions of users. This service cannot be provided by a single physical server due to performance limitations. Thanks to the utilization of names, it is possible to scale this service by mapping a given name to a set of addresses. When a client queries the name service for the server's name, the name service returns one of the addresses in the set. Various strategies can be used to select one particular address inside the set of addresses. A first strategy is to select a random address in the set. A second strategy is to maintain information about the load on the servers and return the address of the less loaded server. Note that the list of server addresses does not need to remain fixed. It is possible to add and remove addresses from the list to cope with load fluctuations. Another strategy is to infer the location of the client from the name request and return the address of the closest server.	Using names solves these problems and provides additional benefits. If the clients are configured with the name of the server, they will query the name service before contacting the server. The name service will resolve the name into the corresponding address. If a server process needs to move from one physical server to another, it suffices to update the name to address mapping on the name service to allow all clients to connect to the new server. The name service also enables the servers to better sustain the load. Assume a very popular server which is accessed by millions of users. This service cannot be provided by a single physical server due to performance limitations. Thanks to the utilization of names, it is possible to scale this service by mapping a given name to a set of addresses. When a client queries the name service for the server's name, the name service returns one of the addresses in the set. Various strategies can be used to select one particular address inside the set of addresses. A first strategy is to select a random address in the set. A second strategy is to maintain information about the load on the servers and return the address of the less loaded server. Note that the list of server addresses does not need to remain fixed. It is possible to add and remove addresses from the list to cope with load fluctuations. Another strategy is to infer the location of the client from the name request and return the address of the closest server.
	cnp3-ebook/principles/naming — English	Mapping a single name onto a set of addresses allows popular servers to dynamically scale. There are also benefits in mapping multiple names, possibly a large number of them, onto a single address. Consider the case of information servers run by individuals or SMEs. Some of these servers attract only a few clients per day. Using a single physical server for each of these services would be a waste of resources. A better approach is to use a single server for a set of services that are all identified by different names. This enables service providers to support a large number of servers processes, identified by different names, onto a single physical server. If one of these server processes becomes very popular, it will be possible to map its name onto a set of addresses to be able to sustain the load. There are some deployments where this mapping is done dynamically in function of the load.	Mapping a single name onto a set of addresses allows popular servers to dynamically scale. There are also benefits in mapping multiple names, possibly a large number of them, onto a single address. Consider the case of information servers run by individuals or SMEs. Some of these servers attract only a few clients per day. Using a single physical server for each of these services would be a waste of resources. A better approach is to use a single server for a set of services that are all identified by different names. This enables service providers to support a large number of servers processes, identified by different names, onto a single physical server. If one of these server processes becomes very popular, it will be possible to map its name onto a set of addresses to be able to sustain the load. There are some deployments where this mapping is done dynamically in function of the load.
	cnp3-ebook/principles/naming — English	Names provide a lot of flexibility compared to addresses. For the network, they play a similar role as variables in programming languages. No programmer using a high-level programming language would consider using hardcoded values instead of variables. For the same reasons, all networked applications should depend on names and avoid dealing with addresses as much as possible.	Names provide a lot of flexibility compared to addresses. For the network, they play a similar role as variables in programming languages. No programmer using a high-level programming language would consider using hardcoded values instead of variables. For the same reasons, all networked applications should depend on names and avoid dealing with addresses as much as possible.
	cnp3-ebook/principles/naming — French	Footnotes	Notes de pied de page
	cnp3-ebook/principles/naming — English	Footnotes	Footnotes
	cnp3-ebook/principles/naming — French	The :term:`hosts.txt` file is not maintained anymore. A historical snapshot from April 1984 is available from http://ftp.univie.ac.at/netinfo/netinfo/hosts.txt	Le fichier :term:`hosts.txt` n'est plus maintenu. Une snapshot historique d'avril 1984 est disponible à l'adresse http://ftp.univie.ac.at/netinfo/netinfo/hosts.txt
	cnp3-ebook/principles/naming — English	The :term:`hosts.txt` file is not maintained anymore. A historical snapshot from April 1984 is available from http://ftp.univie.ac.at/netinfo/netinfo/hosts.txt	The :term:`hosts.txt` file is not maintained anymore. A historical snapshot from April 1984 is available from http://ftp.univie.ac.at/netinfo/netinfo/hosts.txt
	cnp3-ebook/principles/naming — French	See http://www.donelan.com/dnstimeline.html for a time line of DNS related developments.	Voir http://www.donelan.com/dnstimeline.html pour une chronologie des développements liés au DNS.
	cnp3-ebook/principles/naming — English	See http://www.donelan.com/dnstimeline.html for a time line of DNS related developments.	See http://www.donelan.com/dnstimeline.html for a time line of DNS related developments.
	cnp3-ebook/principles/naming — French	This specification evolved later to support domain names written by using other character sets than us-ASCII :rfc:`5890`. This extension is important to support languages other than English, but a detailed discussion is outside the scope of this document.	Cette spécification a évolué par la suite pour prendre en charge les noms de domaine écrits en utilisant d'autres jeux de caractères que us-ASCII :rfc:`5890`. Cette extension est importante pour la prise en charge de langues autres que l'anglais, mais une discussion détaillée sort du cadre de ce document.
	cnp3-ebook/principles/naming — English	This specification evolved later to support domain names written by using other character sets than us-ASCII :rfc:`5890`. This extension is important to support languages other than English, but a detailed discussion is outside the scope of this document.	This specification evolved later to support domain names written by using other character sets than us-ASCII :rfc:`5890`. This extension is important to support languages other than English, but a detailed discussion is outside the scope of this document.
	cnp3-ebook/principles/naming — French	The official list of top-level domain names is maintained by :term:`IANA` at http://data.iana.org/TLD/tlds-alpha-by-domain.txt Additional information about these domains may be found at http://en.wikipedia.org/wiki/List_of_Internet_top-level_domains	La liste officielle des noms de domaine de premier niveau est tenue à jour par :term:`IANA` à l'adresse http://data.iana.org/TLD/tlds-alpha-by-domain.txt. Des informations supplémentaires sur ces domaines sont disponibles à l'adresse http://en.wikipedia.org/wiki/List_of_Internet_top-level_domains
	cnp3-ebook/principles/naming — English	The official list of top-level domain names is maintained by :term:`IANA` at http://data.iana.org/TLD/tlds-alpha-by-domain.txt Additional information about these domains may be found at http://en.wikipedia.org/wiki/List_of_Internet_top-level_domains	The official list of top-level domain names is maintained by :term:`IANA` at http://data.iana.org/TLD/tlds-alpha-by-domain.txt Additional information about these domains may be found at http://en.wikipedia.org/wiki/List_of_Internet_top-level_domains
	cnp3-ebook/principles/naming — French	A copy of the information maintained by each root nameserver is available at http://www.internic.net/zones/root.zone	Une copie des informations maintenues par chaque serveur de noms racine est disponible à l'adresse http://www.internic.net/zones/root.zone
	cnp3-ebook/principles/naming — English	It is interesting to note that to prevent any homograph attack, Google Inc. registered the `g00gle.com` domain name but does not apparently use it.	It is interesting to note that to prevent any homograph attack, Google Inc. registered the `g00gle.com` domain name but does not apparently use it.
	cnp3-ebook/principles/naming — English	A copy of the information maintained by each root nameserver is available at http://www.internic.net/zones/root.zone	A copy of the information maintained by each root nameserver is available at http://www.internic.net/zones/root.zone
	cnp3-ebook/principles/naming — French	It is interesting to note that to prevent any homograph attack, Google Inc. registered the `g00gle.com` domain name but does not apparently use it.	Il est intéressant de noter que pour prévenir toute attaque par homographe, Google Inc. a enregistré le nom de domaine `g00gle.com` mais ne l'utilise apparemment pas.
	cnp3-ebook/principles/naming — English	Until February 2008, the root DNS servers only had IPv4 addresses. IPv6 addresses were slowly added to the root DNS servers to avoid creating problems as discussed in http://www.icann.org/en/committees/security/sac018.pdf As of February 2021, there remain a few DNS root servers that are still not reachable using IPv6. The full list is available at http://www.root-servers.org/	Until February 2008, the root DNS servers only had IPv4 addresses. IPv6 addresses were slowly added to the root DNS servers to avoid creating problems as discussed in http://www.icann.org/en/committees/security/sac018.pdf As of February 2021, there remain a few DNS root servers that are still not reachable using IPv6. The full list is available at http://www.root-servers.org/