Exit Zen
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../../principles/reliability.rst:51
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:math:`10^3`
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../../principles/transport.rst:34
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Bob : `You're welcome`
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../../protocols/dns.rst:52
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The `TTL` field indicates the lifetime of the `Resource Record` in seconds. This field is set by the server that returns an answer and indicates for how long a client or a resolver can store the `Resource Record` inside its cache. A long `TTL` indicates a stable `RR`. Some companies use short `TTL` values for mobile hosts and also for popular servers. For example, a web hosting company that wants to spread the load over a pool of hundred servers can configure its nameservers to return different answers to different clients. If each answer has a small `TTL`, the clients will be forced to send DNS queries regularly. The nameserver will reply to these queries by supplying the address of the less loaded server.
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../../bibliography.rst:51
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Cohen, D., `On Holy Wars and a Plea for Peace`, IEN 137, April 1980, http://www.ietf.org/rfc/ien/ien137.txt
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../../glossary.rst:14
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The American Standard Code for Information Interchange (ASCII) is a character-encoding scheme that defines a binary representation for characters. The ASCII table contains both printable characters and control characters. ASCII characters were encoded in 7 bits and only contained the characters required to write text in English. Other character sets such as Unicode have been developed later to support all written languages.
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../../exercises/ex-sharing.rst:316
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An important part of the CSMA/CD algorithm is the exponential backoff. To illustrate the operation of this algorithm, let us consider a cable that has a length of one kilometer. The bandwidth of the network is set to 10 Mbps. Assume that when a collision occurs, host A always selects the highest possible random delay according to the exponential backoff algorithm while host B always selects the shortest one. In this network, the slot time is equal to the time required to transmit 100 bits. We further assume that a host can detect collision immediately (i.e. as soon as the other frame arrives).
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../../exercises/reliability.rst:35
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The delay between the two hosts is `s` seconds in both directions
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../../exercises/sockets.rst:135
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As the ``sendto`` function is generic, this function will work correctly independently from the fact that the peer's address is defined as a path on the computer filesystem or a network address.
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../../exercises/transport.rst:128
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Amazon provides the `S3 storage service <https://s3.amazonaws.com/>`_ where companies and researchers can store lots of information and perform computations on the stored information. Amazon allows users to send files through the Internet, but also by sending hard-disks. Assume that a 1 Terabyte hard-disk can be delivered within 24 hours to Amazon by courier service. What is the minimum bandwidth required to match the bandwidth of this courier service ?
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../../principles/network.rst:76
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There are two possible organizations for the network layer :
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../../principles/referencemodels.rst:58
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An important point to note about the `Datalink layer` is that although the figure below indicates that two entities of the `Datalink layer` exchange frames directly, in reality this is slightly different. When the `Datalink layer` entity on the left needs to transmit a frame, it issues as many `Data.request` primitives to the underlying `physical layer` as there are bits in the frame. The physical layer will then convert the sequence of bits in an electromagnetic or optical signal that will be sent over the physical medium. The `physical layer` on the right hand side of the figure will decode the received signal, recover the bits and issue the corresponding `Data.indication` primitives to its `Datalink layer` entity. If there are no transmission errors, this entity will receive the frame sent earlier.
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../../principles/reliability.rst:52
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1 Mbps
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../../principles/sharing.rst:62
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Sharing bandwidth
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../../principles/transport.rst:41
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Such a conversation succeeds if both Alice and Bob speak the same language. If Alice meets Tchang who only speaks Chinese, she won't be able to ask him the current time. A conversation between humans can be more complex. For example, assume that Bob is a security guard whose duty is to only allow trusted secret agents to enter a meeting room. If all agents know a secret password, the conversation between Bob and Trudy could be as follows :
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../../protocols/dns.rst:54
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The `RDLength` field is the length of the `RData` field that contains the information of the type specified in the `Type` field.
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../../bibliography.rst:52
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Donahoo, M., Calvert, K., `TCP/IP Sockets in C: Practical Guide for Programmers <http://books.google.com/books?id=dmt_mERzxV4C>`_ , Morgan Kaufman, 2009
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../../glossary.rst:99
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ASN.1
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../../exercises/ex-sharing.rst:343
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Fairness and congestion control
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../../exercises/reliability.rst:36
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there are no transmission errors
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../../exercises/sockets.rst:139
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Receiving data from a peer using a socket
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