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8 ../../protocols/udp.rst:43
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — UDP uses a single segment format shown in the figure below. 59/10000 · 59
8 ../../protocols/wifi.rst:19
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Typical throughput 18/10000 · 18
8 ../../principles/network.rst:47
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Even if we only consider the point-to-point datalink layers, there is an important characteristic of these layers that we cannot ignore. No datalink layer is able to send frames of unlimited size. Each datalink layer is characterized by a maximum frame size. There are more than dozen different datalink layers and unfortunately most of them use a different maximum frame size. This heterogeneity in the maximum frame sizes will cause problems when we will need to exchange data between hosts attached to different types of datalink layers. 540/10000 · 540
8 ../../principles/referencemodels.rst:48
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — An important point to note about the Physical layer is the service that it provides. This service is usually an unreliable service that allows the users of the Physical layer to exchange bits. The unit of information transfer in the Physical layer is the bit. The Physical layer service is unreliable because : 310/10000 · 310
8 ../../protocols/dns.rst:33
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The DNS header contains a series of flags. The `QR` flag is used to distinguish between queries and responses. It is set to `0` in DNS queries and `1` in DNS answers. The `Opcode` is used to specify the query type. For instance, a :term:`standard query` is used when a client sends a `name` and the server returns the corresponding `data`. An update request is used when the client sends a `name` and new `data` and the server then updates its database. 453/10000 · 453
9 ../../exercises/ex-sharing.rst:150
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — In ALOHA, the hosts rely on acknowledgments to detect whether their frame has been received correctly by the destination. Consider a network running at 100 Mbps where the host exchange 1000 bits frames and acknowledgments of 100 bits. Draw the frames sent by hosts A and B in the figure below. Assume that a square corresponds to 10 microseconds and that the cable has a length of 2 kilometers. 394/10000 · 394
9 ../../index.rst:162
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Appendices 10/10000 · 10
9 ../../exercises/sockets.rst:105
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The `DATA` primitives are exchanged through a service access point. In the socket API, the equivalent to the service access point is the `socket`. A `socket` is a data structure which is maintained by the networking stack and is used by the application every time it needs to send or receive data through the networking stack. 326/10000 · 326
9 ../../principles/naming.rst:27
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 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. 482/10000 · 482
9 ../../principles/network.rst:49
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — As a first step, let us assume that we only need to exchange a small amount of data. In this case, there is no issue with the maximum length of the frames. However, there are other more interesting problems that we need to tackle. To understand these problems, let us consider the network represented in the figure below. 321/10000 · 321
9 ../../exercises/network.rst:95
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — When a network specialist designs a network, one of the problems that he needs to solve is to set the metrics the links in his network. In the USA, the Abilene network interconnects most of the research labs and universities. The figure below shows the topology of this network in 2009. 287/10000 · 287
9 ../../exercises/reliability.rst:23
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — a Cyclic Redundancy Check (`CRC`) 33/10000 · 33
9 ../../glossary.rst:116
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Application Programming Interface 33/10000 · 33
9 ../../exercises/transport.rst:63
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — What are the acknowledgments sent by `Host B`. How does `Host A` react and how does it terminate the connection ? 113/10000 · 113
9 ../../principles/referencemodels.rst:50
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the Physical layer may change, e.g. due to electromagnetic interference, the value of a bit being transmitted 109/10000 · 109
9 ../../principles/sharing.rst:95
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A fifth physical organization of a network is the tree. Such networks are typically used when a large number of customers must be connected in a very cost-effective manner. Cable TV networks are often organized as trees. 220/10000 · 220
9 ../../principles/transport.rst:45
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Bob : `Hello` 13/10000 · 13
9 ../../principles/security.rst:113
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — In the above example, `Eve` can capture all the packets exchanged by Bob and Alice. This implies that Eve can discover Alice's username and Alice's password. With this information, Eve can then authenticate as Alice on Bob's computer and do whatever Alice is authorized to do. This is a major problem from a security point of view. To prevent this attack, Alice should never send her password in clear over a network where someone could eavesdrop the information. In some networks, such as an open wireless network, an attacker can easily collect all the data sent by a particular user. In other networks, this is a bit more complex depending on the network technology used, but various software packages exist to automate this process. As will be described later, the best approach to prevent this type of attack is to rely on cryptographic techniques to ensure that passwords are never sent in clear. 902/10000 · 902
9 ../../exercises/dns.rst:36
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `type` is the type of DNS record that is requested by the query such as `NS` for a nameserver, `A` for an IPv4 address, `AAAA` for an IPv6 address, `MX` for a mail relay, ... 174/10000 · 174
9 ../../exercises/email.rst:20
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The Post Office Protocol (POP) is a rather simple protocol described in :rfc:`1939`. POP operates in three phases. The first phase is the authorization phase where the client provides a username and a password. The second phase is the transaction phase where the client can retrieve emails. The last phase is the update phase where the client finalizes the transaction. What are the main POP commands and their parameters ? When a POP server returns an answer, how can you easily determine whether the answer is positive or negative ? 534/10000 · 534