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../../principles/sharing.rst:62
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Sharing bandwidth
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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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../../principles/security.rst:198
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In practice, there is a possibility of denial of service attacks as soon as there is a limited resource somewhere in the network. This resource can be the bandwidth of a link, but it could also be the computational power of a server, its memory or even the size of tables used by a given protocol implementation. Defending against real DoS attacks can be difficult, especially if the attacker controls a large number of sources that are used to launch the attacks. In terms of bandwidth, DoS attacks composed of a few Gbps to a few tens of Gbps of traffic are frequent on the Internet. In 2015, `github.com <http://www.github.com>`_ suffered from a distributed DoS that reached a top bandwidth of 400 Gbps according to some `reports <http://www.techworld.com/news/security/worlds-largest-ddos-attack-reached-400gbps-says-arbor-networks-3595715/>`_.
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../../exercises/dns.rst:48
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When run without any parameter, `dig` queries one of the root DNS servers and retrieves the list of the names of all root DNS servers. For technical reasons, there are only 13 different root DNS servers. This information is also available as a text file from http://www.internic.net/zones/named.root. What are the IPv6 addresses of all these servers?
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../../exercises/http.rst:50
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Footnotes
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../../exercises/ipv6.rst:45
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The forwarding paths used in a network depend on the forwarding tables installed in the network nodes. Sometimes, these forwarding tables must be configured manually.
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../../exercises/lan.rst:93
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Most commercial Ethernet switches are able to run the Spanning tree protocol independently on each VLAN. What are the benefits of using per-VLAN spanning trees ?
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../../exercises/routing-policies.rst:153
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How is the reachability of these addresses affected when link `R1`-`R3` fails ?
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../../exercises/routing-protocols.rst:241
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The first packet that this router received his a Hello packet that was sent by router ``r2``. There are several interesting points to note about this packet. First, its source address is the link-local address (``fe80::68bc:b4ff:fe19:42b7``) of router ``r2`` on this interface. The destination address of the packet is reserved IPv6 multicast address for OSPFv3, i.e. ``ff02::5``. The Hop Limit of the packet is set to 1 and OSFPv3 uses a next header of type 89.
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../../exercises/tcp-2.rst:86
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Each line of a packetdrill_ script starts with a `timing` parameter that indicates at what time the event specified on this line should happen. packetdrill_ supports absolute and relative timings. An absolute timing is simply a number that indicates the delay in seconds between the start of the script and the event. A relative timing is indicated by using ``+`` followed by a number. This number is then the delay in seconds between the previous event and the current line. Additional information may be found in [CCB+2013]_.
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../../exercises/trace.rst:94
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The wireshark_ window is divided in three parts. The top part of the window is a summary of the first packets from the trace. By clicking on one of the lines, you can show the detailed content of this packet in the middle part of the window. The middle of the window allows you to inspect all the fields of the captured packet. The bottom part of the window is the hexadecimal representation of the packet, with the field selected in the middle window being highlighted.
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../../protocols/bgp.rst:57
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over a `customer->provider` relationship, the `customer` domain advertises to its `provider` its own prefixes and all the routes that it has learned from its own customers.
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../../protocols/congestion.rst:91
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Initial congestion window
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../../protocols/dnssec.rst:166
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the `RRSIG` record is used to encode the signature of a DNS record. This record contains several sub-fields. The most important ones are the algorithm used to generate the signature, the identifier of the public key used to sign the record, the original TTL of the signed record and the validity period for the signature.
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../../protocols/email.rst:100
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The sender address. This header line starts with `From:`. This contains the (optional) name of the sender followed by its email address between `<` and `>`. Email addresses are always composed of a username followed by the `@` sign and a domain name.
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../../protocols/ethernet.rst:94
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An Ethernet network provides an unreliable connectionless service. It supports three different transmission modes : `unicast`, `multicast` and `broadcast`. While the Ethernet service is unreliable in theory, a good Ethernet network should, in practice, provide a service that:
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../../protocols/http.rst:75
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The first component of a URI is its `scheme`. A `scheme` can be seen as a selector, indicating the meaning of the fields after it. In practice, the scheme often identifies the application-layer protocol that must be used by the client to retrieve the document, but it is not always the case. Some schemes do not imply a protocol at all and some do not indicate a retrievable document [#furiretrieve]_. The most frequent schemes are `http` and `https`. We focus on `http` in this section. A URI scheme can be defined for almost any application layer protocol [#furilist]_. The characters `:` and `//` follow the `scheme` of any URI.
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../../protocols/ipv6.rst:91
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SIPP proposed in :rfc:`1710`
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../../protocols/ppp.rst:37
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The IANA maintains the registry of all assigned PPP protocol fields at : http://www.iana.org/assignments/ppp-numbers
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../../protocols/routing.rst:50
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Each RIP message contains a set of route entries. Each route entry is encoded as a 20 bytes field whose format is shown below. RIP was initially designed to be suitable for different network layer protocols. Some implementations of RIP were used in XNS or IPX networks :rfc:`2453`. The format of the route entries used by :rfc:`2080` is shown below. `Prefix length` is the length of the subnet identifier in bits and the `metric` is encoded as one byte. The maximum metric supported by RIP is `15`.
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