Exit Zen
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../../index.rst:86
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Part 3: Practice
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../../glossary.rst:117
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API
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../../exercises/ex-sharing.rst:119
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Same question as above, but now consider that the hosts transmit 1000 bits frames at 100 Mbps. The cable has a length of 2 kilometers. C is in the middle of the cable. Each square in the figure below corresponds to 10 microseconds.
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../../exercises/reliability.rst:25
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a `length` field that indicates the length of the data
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../../exercises/network.rst:92
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The Abilene network
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../../exercises/sockets.rst:105
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`DATA.indication(message)` is issued by the transport service to deliver a message to the application. In the socket API, this corresponds to the return of the ``recv`` method that is called by the application.
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../../exercises/transport.rst:57
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What are the acknowledgments sent by `Host B`. How does `Host A` react and how does it terminate the connection ?
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../../principles/naming.rst:23
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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.
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../../principles/referencemodels.rst:34
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Starting from the bottom, the first layer is the Physical layer. Two communicating devices are linked through a physical medium. This physical medium is used to transfer an electrical or optical signal between two directly connected devices.
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../../principles/network.rst:29
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The second type of datalink layer is the one used in Local Area Networks (LAN). Conceptually, a LAN is a set of communicating devices such that any two devices can directly exchange frames through the datalink layer. Both hosts and routers can be connected to a LAN. Some LANs only connect a few devices, but there are LANs that can connect hundreds or even thousands of devices. In this chapter, we focus on the utilization of point-to-point datalink layers. We describe later the organization and the operation of Local Area Networks and their impact on the network layer.
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../../principles/reliability.rst:39
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The physical layer
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../../principles/transport.rst:27
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An `application-level protocol` is similar to a structured conversation between humans. Assume that Alice wants to know the current time but does not have a watch. If Bob passes close by, the following conversation could take place :
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../../principles/security.rst:73
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The first type of attacker is called the `passive attacker`. A `passive attacker` is someone able to observe and usually store the information (e.g. the packets) exchanged in a given network or subset of it (e.g. a specific link). This attacker has access to all the data passing through this specific link. This is the most basic type of attacker and many network technologies are vulnerable to such attacks. In the above example, a passive attacker could easily capture the password sent by Alice and reuse it later to be authenticated as Alice on the remote computer. This is illustrated in the figure below where we do not show anymore the ``DATA.req`` and ``DATA.ind`` primitives but only the messages exchanged. Throughout this chapter, we will always use `Eve` as a user who is able to eavesdrop the data passing in front of her.
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../../exercises/dns.rst:35
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`server` is the IP address or the name of a DNS server or resolver
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../../exercises/email.rst:18
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The TCP protocol supports 65536 different ports numbers. Many of these port numbers have been reserved for some applications. The official repository of the reserved port numbers is maintained by the Internet Assigned Numbers Authority (IANA_) on http://www.iana.org/assignments/port-numbers [#fservices]_. Using this information, what is the default port number for the POP3 protocol ? Does it run on top of UDP or TCP ?
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../../exercises/http.rst:25
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HTTP 1.1, specified in :rfc:`2616`, forces the client to include the `Host:` header in all its requests. HTTP 1.0 does not define the `Host:` header, but most implementations support it. By using `telnet` and `curl` retrieve the first page of the https://www.computer-networking.info web server [#fhttps]_ by sending http requests with and without the `Host:` header. Explain the difference between the two.
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../../exercises/ipv6.rst:35 • ../../exercises/ipv6.rst:144 • ../../exercises/ipv6.rst:222
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host ``A`` : ``2001:db8:1341:1::A`` and its default route points to ``2001:db8:1341:1::1``
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../../exercises/lan.rst:62
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Fig. 2. A typical enterprise backbone network
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../../exercises/routing-policies.rst:63 • ../../exercises/routing-policies.rst:96
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Consider the interdomain topology shown in the figure below. Assuming, that `AS1` advertises prefix ``2001:db8:1::/48``, `AS2` prefix ``2001:db8:2::/48``, ... compute the routing tables of the different ASes.
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../../exercises/routing-protocols.rst:106
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The script starts the routers and hosts.
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