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5 ../../principles/transport.rst:38
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — There are various types of servers as well as various types of clients. A web server provides information in response to the query sent by its clients. A print server prints documents sent as queries by the client. An email server forwards towards their recipient the email messages sent as queries while a music server delivers the music requested by the client. From the viewpoint of the application developer, the client and the server applications directly exchange messages (the horizontal arrows labeled `Queries` and `Responses` in the above figure), but in practice these messages are exchanged thanks to the underlying layers (the vertical arrows in the above figure). In this chapter, we focus on these horizontal exchanges of messages. 746/10000 · 746
6 ../../exercises/sockets.rst:100
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A detailed discussion of the socket API is outside the scope of this section and the references cited above provide a detailed discussion of all the details of the socket API. As a starting point, it is interesting to compare the socket API with the service primitives that we have discussed in the previous chapter. Let us first consider the connectionless service that consists of the following two primitives : 414/10000 · 414
6 ../../exercises/ex-sharing.rst:66
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — In a shared medium, a collision may happen if two hosts transmit at almost the same time as shown in the example below. 119/10000 · 119
6 ../../index.rst:40
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Part 1: Principles 18/10000 · 18
6 ../../principles/naming.rst:21
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 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. 794/10000 · 794
6 ../../principles/network.rst:40
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — There are two main types of datalink layers. The simplest datalink layer is when there are only two communicating systems that are directly connected through the physical layer. Such a datalink layer is used when there is a point-to-point link between the two communicating systems. These two systems can be hosts or routers. PPP (Point-to-Point Protocol), defined in :rfc:`1661`, is an example of such a point-to-point datalink layer. Datalink layer entities exchange `frames`. A datalink :term:`frame` sent by a datalink layer entity on the left is transmitted through the physical layer, so that it can reach the datalink layer entity on the right. Point-to-point datalink layers can either provide an unreliable service (frames can be corrupted or lost) or a reliable service (in this case, the datalink layer includes retransmission mechanisms). 850/10000 · 850
6 ../../exercises/network.rst:25
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The network below uses port forwarding with flat addresses. The network boots and all hosts start one after the other. Explain at each step how the packets are forwarded and how the port forwarding tables of the network nodes are modified. Host `C` sends a packet to host `B`. Some time later, host `A` sends a packet to host `C`. Finally, host `B` sends a packet to host `A`. 376/10000 · 376
6 ../../exercises/reliability.rst:19
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A version of the Alternating Bit Protocol supporting variable length frames uses a header that contains the following fields : 126/10000 · 126
6 ../../glossary.rst:15
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — anycast 7/10000 · 7
6 ../../exercises/transport.rst:24
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A reliable connection oriented transport places a 32 bits sequence number inside the segment header to number the segments. This sequence number is incremented for each data segment. The connection starts as shown in the figure below : 235/10000 · 235
6 ../../principles/referencemodels.rst:42
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The Physical layer 18/10000 · 18
6 ../../principles/sharing.rst:39
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The second possible physical organization, which is also used inside computers to connect different extension cards, is the bus. In a bus network, all hosts are attached to a shared medium, usually a cable through a single interface. When one host sends an electrical signal on the bus, the signal is received by all hosts attached to the bus. A drawback of bus-based networks is that if the bus is physically cut, then the network is split into two isolated networks. For this reason, bus-based networks are sometimes considered to be difficult to operate and maintain, especially when the cable is long and there are many places where it can break. Such a bus-based topology was used in early Ethernet networks. 714/10000 · 714
6 ../../principles/transport.rst:40
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Networked applications do not exchange random messages. In order to ensure that the server is able to understand the queries sent by a client, and also that the client is able to understand the responses sent by the server, they must both agree on a set of syntactical and semantic rules. These rules define the format of the messages exchanged as well as their ordering. This set of rules is called an application-level `protocol`. 432/10000 · 432
6 ../../protocols/dns.rst:24
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The DNS header 14/10000 · 14
6 ../../principles/security.rst:62
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Threats 7/10000 · 7
6 ../../exercises/dns.rst:27
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A typical usage of dig is as follows: 37/10000 · 37
6 ../../exercises/email.rst:13
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Telnet is a protocol that allows to obtain a terminal on a remote server. For this, telnet opens a TCP connection with the remote server on port 23. However, most `telnet` implementations allow the user to specify an alternate port as `telnet hosts port` When used with a port number as parameter, `telnet` opens a TCP connection to the remote host on the specified port. `telnet` can thus be used to test any server using an ASCII-based protocol on top of TCP. Note that if you need to stop a running `telnet` session, ``Ctrl-C`` will not work as it will be sent by `telnet` to the remote host over the TCP connection. On many `telnet` implementations you can type ``Ctrl-]`` to freeze the TCP connection and return to the telnet interface. 741/10000 · 741
6 ../../exercises/http.rst:22
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Can you explain the different headers placed by curl_ in the request ? 70/10000 · 70
6 ../../exercises/ipv6.rst:31
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Design questions 16/10000 · 16
6 ../../exercises/lan.rst:31
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Consider the switched network shown in the figure below. Compute the Spanning Tree of this network. 99/10000 · 99