Computer Networks and Internet Standards
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Questions and Answers

When the ISO and the IEEE both issue standards for the same artefact, architecture, or process and the standards disagree, what should be done?

  • For engineering cases, the IEEE standard has precedence, while the ISO standard takes precedence in most other cases. (correct)
  • The ISO standard takes precedence.
  • It does not matter, because standards are not binding.
  • The IEEE standard takes precedence.
  • Both standards should be ignored until they have been harmonised.

    • IEEE 802.11ax is better known as:

  • WiFi 7
  • WiFi 4
  • WiFi 3
  • WiFi 6 (correct)
  • WiFi 5

    • Which historical event had a profound impact on many design decisions for the Internet (or ARPAnet then)?

  • Rise of the Global South
  • Cold War (correct)
  • Suez Canal Crisis
  • Bay of Pigs Invasion
  • Lockerbie Bombing

    • The RIR for Europe is:

    <p>RIPE</p> Signup and view all the answers

    Which ISO OSI layer is responsible for regulating which node is allowed to transmit next in cases where two computers are directly connected?

    <p>2</p> Signup and view all the answers

    The phrase 'protocol stack' is used in a network context because:

    <p>Protocols are 'stacked' in layers on top of one another.</p> Signup and view all the answers

    Protocols such as SMTP, POP3, and FTP are deemed to be application layer protocols. In addition, they often include functionality associated with the following ISO OSI layer(s):

    <p>Layers 5 and 4</p> Signup and view all the answers

    When an email client transmits an email via SMTP, it may usually connect to the following port(s) for cleartext transmissions:

    <p>25</p> Signup and view all the answers

    Which protocol will a discless computer typically use to transfer an operating system image from a server to the computer, when the computer boots?

    <p>TFTP</p> Signup and view all the answers

    Which of the following statements about X.509 is/are true?

    <p>All of the above</p> Signup and view all the answers

    Which ISO OSI layer may provide checkpoints, such that only messages sent since the last checkpoint have to be retransmitted after a connection has been lost?

    <p>4</p> Signup and view all the answers

    How are the SYN and ACK packets sent during a TCP handshake differentiated from one another?

    <p>The sequence and acknowledgement numbers determine the type of packet; a sequence number of 0, for example, indicates that it is a SYN packet and a sequence number of 0 and an acknowledgement number of 1 indicate that it is a SYN+ACK packet.</p> Signup and view all the answers

    How does the server differentiate between the ACK packet received as the last part of the handshake to establish a connection and an ACK packet that acknowledges data?

    <p>The ACK flag is only set for the handshake packet; the acknowledgement field is used to acknowledge data.</p> Signup and view all the answers

    What is the minimum number of timer types required by any sliding window ARQ protocol?

    <p>1</p> Signup and view all the answers

    The TCP quiet timer determines when a port may be used for a new TCP connection after a previous connection has been closed. Which of the following claims is/are true?

    <p>The port (or socket) is in the TIME_WAIT state while the quiet timer is active.</p> Signup and view all the answers

    Which command enables one to see the status of transport layer connections on a host (in most operating systems)?

    <p>netstat</p> Signup and view all the answers

    What type of port is port 55555?

    <p>Practical</p> Signup and view all the answers

    What does the claim that QUIC is a quick protocol mean?

    <p>It reduces latency when establishing or re-establishing a connection.</p> Signup and view all the answers

    Which of the following actions always happen(s) when a client establishes a QUIC connection with a server?

    <p>The client sends an initial packet numbered 0 on the wire.</p> Signup and view all the answers

    QUIC connections can migrate. Which party can initiate such a migration in QUICv1 or QUICv2?

    <p>More than one of the above</p> Signup and view all the answers

    Which of the following headers are always present in a long QUIC header? Include cases where the length of the field will be present and may be 0, meaning that the field itself may be omitted.

    <p>All of the above</p> Signup and view all the answers

    Assume a client establishes a new QUIC connection at time t0 with a server. The server receives the initial packet at time t1 and immediately sends its response(s). This process continues with the client transmitting at even times (t0, t2, t4, …) and the server transmitting at odd times (t1, t3, t5, …). What is the soonest time at which application data may (sometimes) be sent?

    <p>t2</p> Signup and view all the answers

    Assume a client establishes a new QUIC connection at time t0 with a server. The server receives the initial packet at time t1 and immediately sends its response(s). This process continues with the client transmitting at even times (t0, t2, t4, …) and the server transmitting at odd times (t1, t3, t5, …). What is the soonest time at which 1-RTT application data may (sometimes) be sent?

    <p>t3</p> Signup and view all the answers

    Assume a client establishes a new QUIC connection at time t0 with a server. The server receives the initial packet at time t1 and immediately sends its response(s). This process continues with the client transmitting at even times (t0, t2, t4, …) and the server transmitting at odd times (t1, t3, t5, …). What is the soonest time at which the connection may be deemed to be fully established?

    <p>t3</p> Signup and view all the answers

    Study Notes

    Standards and Protocols

    • ISO and IEEE standards:
      • In case of disagreement, no standard takes precedence
      • Adoption of standards may be mandated by external processes
    • IEEE 802.11ax is also known as WiFi 6

    Internet History

    • Cold War had a profound impact on design decisions for the Internet (or ARPAnet)

    Network Architecture

    • RIR (Regional Internet Registry) for Europe is RIPE
    • ISO OSI layer 2 is responsible for regulating node transmission in directly connected computers

    Protocol Stack

    • Protocols are "stacked" in layers, with each layer building on the previous one
    • The concept of a protocol stack is used in networking

    Email Protocols

    • SMTP, POP3, and FTP are application layer protocols
    • They often include functionality associated with lower OSI layers
    • SMTP servers can be identified by searching the internet and attempting to connect to relevant ports
    • Email clients usually connect to port 25 or 587 for cleartext transmissions

    File Transfer Protocol (FTP)

    • FTP is based on a client-server architecture

    Sockets and Servers

    • A program acting as a server needs to specify the port on the server
    • A CGI program sends output to a browser by writing to standard output and receives input from a browser by reading from standard input

    DNS and Name Resolution

    • A file on a name server that maps names to IP addresses is known as a hosts file
    • The command nslookup ns1.up.ac.za 8.8.8.8 would resolve ns1.up.ac.za using the default DNS server and ignore 8.8.8.8

    Character Encoding and Unicode

    • When computers with different character encodings communicate, challenges may arise
    • Unicode characters can be represented in UTF-8 using up to 4 bytes
    • The value of n for the number of Unicode characters that can be represented in UTF-8 using exactly 4 bytes is 21

    Email and MIME

    • An email consisting of an HTML message and a JPG image would have a MIME type of multipart/mixed
    • The Content-Transfer-Encoding for transferring a PNG image via SMTP would be base64

    Security and Encryption

    • Encryption should be placed on ISO OSI layer 7 (application layer) if desired
    • X.509 is used for public key cryptography and is part of the X.500 series of standards

    Network Management

    • SNMP, CMIP, and CMOT are examples of network management protocols
    • BGP is an external gateway protocol (EGP)

    Routing and Routing Protocols

    • RIP is an example of an internal gateway protocol (IGP)
    • Counting to infinity is a concern in RIP
    • OSPF is an IGP, and BGP is an EGP

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    2024_COS_332_MCQ.pdf

    Description

    Test your knowledge of computer networks, internet standards, and protocols. This quiz covers topics such as ISO and IEEE standards, internet history, and network architecture.

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