Exit Zen
21
../../protocols/transport-service.rst:60
English
`0:0:0:0:0:0:0:1` is represented as `::1`
0/410 · 41
21
../../protocols/udp.rst:71
English
The checksum of the UDP segment is computed over :
0/500 · 50
21
../../protocols/wifi.rst:24
English
802.11b
0/100 · 7
22
../../bibliography.rst:68
English
Sally Floyd and Van Jacobson. 1993. `Random early detection gateways for congestion avoidance <https://dx.doi.org/10.1109/90.251892>`_. IEEE/ACM Transactions Networking 1, 4 (August 1993), 397-413.
0/1970 · 197
22
../../glossary.rst:235
English
BNF
0/100 · 3
22
../../exercises/ex-sharing.rst:538 • ../../exercises/ex-sharing.rst:613
English
Consider the network depicted in the figure below.
0/500 · 50
22
../../exercises/reliability.rst:50
English
Practice
9/100 · 8
22
../../exercises/network.rst:182 • ../../exercises/network.rst:214
English
Same question with virtual circuits.
41/360 · 36
22
../../exercises/sockets.rst:216
English
``connect``: connecting a socket to a remote address
54/520 · 52
22
../../exercises/transport.rst:146
English
Consider a transport protocol that provides the bytestream service and uses 32 bits sequence number to represent the position of the first byte of the payload of DATA segments in the bytestream. How would you modify this protocol so that it can provide a message-mode service ? Consider first short messages that always fit inside a single segment. In a second step, discuss how you could support messages of unlimited size.
526/4240 · 424
22
../../principles/naming.rst:117
English
To be able to contact the root nameservers, each DNS client must know their addresses. This implies, that DNS clients must maintain an up-to-date list of the addresses of the root nameservers. Without this list, it is impossible to contact the root nameservers. Forcing all Internet hosts to maintain the most recent version of this list would be difficult from an operational point of view. To solve this problem, the designers of the DNS introduced a special type of DNS server : the DNS resolvers. A :term:`resolver` is a server that provides the name resolution service for a set of clients. A network usually contains a few resolvers. Each host in these networks is configured to send all its DNS queries via one of its local resolvers. These queries are called `recursive queries` as the :term:`resolver` must recursively send requests through the hierarchy of nameservers to obtain the `answer`.
979/9020 · 902
22
../../principles/network.rst:89
English
the information to be sent
23/260 · 26
22
../../principles/reliability.rst:63
English
On the sender side :
23/200 · 20
22
../../principles/security.rst:287
English
With the Kerckhoff principle, we can now discuss a simple but powerful encryption scheme that relies on the `XOR` logic operation. This operation is easily implemented in hardware and is supported by all microprocessors. Given a secret, :math:`K`, it is possible to encode a message `M` by computing :math:`C_M = K \oplus M`. The receiver of this messages can recover the original message as since :math:`M = K \oplus (K \oplus M)`. This `XOR` operation is the key operation of the perfect cipher that is also called the Vernam cipher or the one-time pad. This cipher relies on a key that contains purely random bits. The encrypted message is then produced by XORing all the bits of the message with all the bits of the key. Since the key is random, it is impossible for an attacker to recover the original text (or plain text) from the encrypted one. From a security viewpoint, the one-time-pad is the best solution provided that the key is as long as the message.
0/9650 · 965
22
../../exercises/dns.rst:59
English
Use `dig` to find the mail relays used by the `uclouvain.be` and `student.uclouvain.be` domains. What is the `TTL` of these records ? Can you explain the preferences used by the `MX` records. You can find more information about the MX records in :rfc:`5321`.
0/2580 · 258
22
../../exercises/ipv6.rst:193
English
How do you configure the forwarding tables on ``R1`` and ``R4`` so that ``A`` can reach ``B`` and the reverse ?
0/1110 · 111
22
../../exercises/lan.rst:246
English
The first part of the output of the :manpage:`brctl(8)` command shows the state of the Spanning Tree software on the switch. The identifier of this switch is ``0003.f63545ab5f79`` and the root switch is itself. There is no root port on this switch since it is the root. The path cost is the cost of the path to reach the root switch, i.e. 0 on the root. Then the switch reports the different timers.
0/3990 · 399
22
../../exercises/routing-policies.rst:193
English
`Section 3.3 <https://tools.ietf.org/html/rfc4443#section-3.3>`_ of :rfc:`4443` explains two different reasons why an IPv6 enabled device could generate an ICMPv6 Time Exceeded message. Explain when a router could generate such a message with ``Code==0`` and when a host could generate such a message with ``Code==1``.
0/3180 · 318
22
../../exercises/routing-protocols.rst:269
English
A more detailed discussion of the packets that routing protocols exchange may be found in [Goralski2009]_.
0/1060 · 106
22
../../exercises/tcp-2.rst:123
English
In the example above, packetdrill_ injects a segment containing two bytes. This segment is acknowledged and after that the :manpage:`read` system call succeeds and reads the available data with a buffer of 1000 bytes. It returns the amount of read bytes, i.e. ``2``.
0/2660 · 266