2024_COS_332_MCQ.pdf

2024 ST 1 & 2 MCQ 1. When the ISO and the IEEE both issue standards for the same artefact, architecture, or process and the standards disagree: A: The ISO standard takes precedence. B: The IEEE standard takes precedence. C: Both standards should be ignored until they have b...

2024 ST 1 & 2 MCQ 1. When the ISO and the IEEE both issue standards for the same artefact, architecture, or process and the standards disagree: A: The ISO standard takes precedence. B: The IEEE standard takes precedence. C: Both standards should be ignored until they have been har- monised. D: For engineering cases, the IEEE standard has precedence, while the ISO standard takes precedence in most other cases. E: It does not matter, because standards are not binding. Adoption of standards may be mandated by processes out- side the standards bodies, though. 2. IEEE 802.11ax is better known as: A: WiFi 3 B: WiFi 4 C: WiFi 5 D: WiFi 6 E: WiFi 7 3. Which historical event had a profound impact on many design decisions for the Internet (or ARPAnet then)? A: Cold War B: Suez Canal Crisis C: Rise of the Global South D: Bay of Pigs Invasion E: Lockerbie Bombing 4. The RIR for Europe is: A: RIPE B: EurNIC C: EuroNIC D: EurIN E: EPIR 5. Which ISO OSI layer is responsible for regulating which node is allowed to transmit next in cases where two computers are directly connected? A: 5 B: 4 C: 3 D: 2 E: It may be 2 or 5 depending on factors not mentioned in the question. 6. The phrase “protocol stack” is used in a network context because: 1  A: Protocols are “stacked” in layers on top of one another. B: A message is “pushed” down when transmitted and then “popped” at the receiving end such that the most recently sent message is the first one that would be retrieved by the receiver. C: Alternative protocols may exist “next to” one another within the layers of protocols. Examples include IPv4 and IPv6. D: Many protocols on the higher layers (such as layer 4) tend to converge into one protocol (or very few protocols) on layer 4. From layer 4 it “spreads out” to many lower layer protocols (especially on layers 2 and 1). E: The notion of a protocol stack is not used in networking. 7. Protocols such as SMTP, POP3, and FTP are deemed to be application layer protocols. As such, they obviously include ISO OSI layer 7 func- tionality. In addition, they often include functionality associated with the following ISO OSI layer(s): A: Only layer 6 B: Layers 6 and 5 C: Layers 5 and 4 D: Layers 4 and 3 E: Only layer 3 8. When an email client (such as Outlook or Thunderbird) transmits an email via SMTP, in practice, it may usually connect to the following port(s) (for cleartext transmissions): A: 25 B: 110 C: 587 D: More than one of the above E: Any of the above 9. Suppose one searches the Internet for SMTP servers. This may, for ex- ample, be done by crawling the Internet and attempting to connect to the relevant SMTP ports and initiating the SMTP exchange of messages. Those where one is able to successfully exchange more than one request and response are deemed to be SMTP servers. Note that one may in- crease the chances of finding SMTP servers by targeting hosts where the FQDN starts with “mail” or “smtp.” Suppose that for any such server, one continues with the exchange of SMTP requests to send an email from [email protected] to [email protected]. In general, one would observe the following outcome: A: The server accepts the requests and forwards the message to xx.org.za for further processing. B: The server accepts the requests but discards the message without an error message. 2  C: The server accepts the requests, discards the message, and sends an error message to [email protected]. D: The server continues the interaction but reports that it does not relay messages. The message is never accepted. E: None of the above, because it is impossible to find SMTP servers that will initiate a conversation without first requiring login creden- tials. 10. When an email is sent using SMTP, the From: header displayed to the recipient is (in the vast majority of cases) based on: A: What was included as the parameter to the rcpt from: SMTP command. B: What was included as the parameter to the helo or ehlo SMTP command. C: The domain of the user from where the email originated. D: A header included as part of the message that followed the data SMTP command. E: What was included as the parameter to the mail from: SMTP command. 11. After an SMTP client has sent a DATA command, it will usually send several lines of data. It signals to the server that the entire data block has been transmitted by sending the following line: A: /DATA B: QUIT C:. D: A blank line E: FIN 12. The Host: line (including the name of the host as specified in the URL) forms one of the headers in an HTTP GET request. Why is it necessary? A: Security (access control). A user should not be able to access an unknown web server using only the address of the server. B: Security (integrity). Connecting to the server and informing the server about the expected domain ensures that an incorrect site would not be served. C: Virtual hosting. The server may host more than one site. D: There is no such Host: header. E: There is no GET request in HTTP. Some other HTTP requests may include a Host: header. 13. FTP is based on the … architecture. A: Client-server B: Peer-to-peer C: Client-server-client-server D: Host-to-host 3  E: Multitier 14. Suppose user u is using server s from workstation w. User u sees graphical output on w that is produced on s. Which protocol(s) may be used to transfer the images from s to w? A: X11 B: Telnet C: HTML D: More than one of the above E: Any of the above 15. A program that wants to open a socket in order to act as a server needs to specify the following: A: The address of the server B: The address of the client C: The port on the server D: The port on the client E: More than one of the above 16. (i) How does a CGI program send output to a browser? (ii) How does a CGI program receive input from a browser? A: (i) Writes to standard output; (ii) Reads from standard input B: (i) Writes to the appropriate socket; (ii) Reads from standard input C: (i) Writes to standard output; (ii) Reads from the appropriate socket D: (i) Writes to the appropriate socket; (ii) Reads from the appropri- ate socket E: (i) Writes to standard output; (ii) Reads an environment variable set by the server 17. A file on a name server that maps names to IP addresses is known as a… file. A: Name B: Hosts C: Mapping D: Resolution E: None of the above 18. When one enters the command nslookup ns1.up.ac.za 8.8.8.8 A: ns1.up.ac.za will be resolved using the default DNS server and 8.8.8.8 will be ignored. B: ns1.up.ac.za will be resolved using the default DNS server and 8.8.8.8 will be reported as 8.8.8.8, since it is already an IP address. 4  C: ns1.up.ac.za will be resolved using the default DNS server and 8.8.8.8 will be reverse resolved (to dns.google) using the same server. D: 8.8.8.8 will be reverse resolved (to dns.google) using ns1.up.ac.za. E: ns1.up.ac.za will be resolved using dns.google. 19. To determine the address of a ‘.com’ name server, one would set the query type to NS and then submit the following query for resolution: A:.com B: com C: *.com D: com. E: com.root 20. The.io TLD is a(n) A: sTLD B: ccTLD C: gTLD D: Reserved TLD E: None of the above 21. Which protocol will a discless computer typically use to transfer an op- erating system image from a server to the computer, when the computer boots? A: DHCP B: FTP C: TFTP D: HTTP E: BOOTP 22. Which of the following are examples of network management protocols? A: SNMP B: CMIP C: CMOT D: More than one of the above E: All of the above 23. Which of the following statements about X.509 is/are true? A: It is part of the X.500 series of standards introduced by CCITT. B: It is used for public key cryptography. C: It is used in the TCP/IP context. D: More than one of the above E: All of the above 24. Which of the following protocols is an / are examples of an external gate- way protocol (EGP)? A: BGP 5  B: OSPF C: RIP D: More than one of the above E: All of the above 25. In which of the following algorithms is counting to infinity a cause for concern? A: Dijkstra B: Bellman-Ford C: RIP D: More than one of the above E: All of the above 26. Consider a scenario in RIP where a router r sends its routing table to a router s. An entry in r’s table indicates that it can reach a network n at a cost of 5. Before receiving the message, the routing table at s indicated that it could reach n at a cost of 8. What will the cost from s to n be according to the routing table at s after s processed the message from r? A: 5 B: 6 C: 7 D: 8 E: More information about r is required to answer the question. 27. Suppose computers A and B both use extended ASCII to represent char- acters. There is no character conversion mechanism between A and B. As- sume that every byte transmitted will be received correctly; no data loss or transmission errors will occur. What challenge(s) may be experienced when these two computers communicate? A: When A sends a digit or one of the 26 Latin characters (in either lower or uppercase) the recipient may interpret at least one of these 62 characters incorrectly. B: A may mark up a character (for example, ë) and such char- acters may be received incorrectly at the destination. C: It is possible that at least one of the following seven punctuation marks may not be communicated correctly: ? ! ,. : " &. D: These computers will not experience any challenges since they use the same character encoding. E: None of the problems listed above will occur (but other challenges may exist). 28. How many Unicode characters can, in principle, be represented in UTF-8 using exactly four bytes? If the answer is expressed in the form (2^n), what is the value of n? A: 14 B: 20 6  C: 21 D: 22 E: 27 29. Suppose an email consists of a message encoded in HTML and a JPG image (both included in the message). These two items are the only com- ponents of the email message. Which MIME type will be used to describe the entire email message? A: application/email B: application/rfc822 C: multipart/alternative D: multipart/mixed E: text/html 30. Which Content-Transfer-Encoding would be most appropriate to transfer a PNG image via SMTP? A: 8bit B: binary C: quoted-printable D: base64 E: 7bit 31. On which ISO OSI layer should encryption be placed (if encryption is desired)? A: 7 B: 6 C: 4 D: 3 E: It depends on factors not mentioned in the question. All of the layers mentioned above are options. 32. 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? A: 2 B: 3 C: 4 D: 5 E: 6 33. How are the SYN and ACK packets sent during a TCP handshake differ- entiated from one another? A: The flags are used to determine the type of handshake packet. B: These packets carry a phantom byte in which the type (SYN or ACK) is encoded. 7  C: 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. D: More than one of the above E: All of the above 34. How does the server differentiate between the ACK packet that it receives as the last part of the handshake to establish a connection, and an ACK packet that acknowledges data that has been received? A: The handshake ACK packet will always be received before the first data acknowledgement packet. B: The ACK flag is only set for the handshake packet; the acknowl- edgement field is used to acknowledge data. C: For a handshake packet, the SYN or FIN flag will be set; for packets that acknowledge data neither will be set. D: The acknowledgement packet that acknowledges the server’s SYN+ACK packet is always part of the handshake; packets that acknowledge other data are not. E: None of the above 35. What is the minimum number of timer types required by any sliding win- dow ARQ protocol? A: 1 B: 2 C: 3 D: 4 E: 5 36. 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? A: The port (or socket) is in the TIME_WAIT state while the quiet timer is active. B: The quiet timer is activated when the FIN+ACK message is sent. C: The quiet timer solves the problem of a packet from a previous connection to be deemed part of a new connection. D: More than one of the above E: All of the above 37. Which command enables one to see the status of transport layer connec- tions on a host (in most operating systems)? A: netstat B: ping C: tracert/traceroute D: tcp-show 8  E: ps 38. What type of port is port 55555? A: Registered B: Well-known C: Dynamic D: Practical E: Temporary 39. What does the claim that QUIC is a quick protocol mean? A: It manages the lower layers to transmit raw data at higher bit rates. B: It reduces latency when establishing or re-establishing a connec- tion.** C: Where multiple parts of a message have to be transported it en- sures that parts of the message are delivered quickly even if some parts are delayed. D: More than one of the above E: All of the above 40. Which of the following actions always happen(s) when a client establishes a QUIC connection with a server? A: The client chooses a connection ID to be used by the server. B: The client includes initial data encrypted with the server’s public key. C: The client informs the server which cryptographic suite will be used. D: The client sends an initial packet numbered 0 on the wire. E: None of the above 41. QUIC connections can migrate. Which party can initiate such a migration in QUICv1 or QUICv2? A: The client B: The server C: The network management system D: More than one of the above E: All of the above 42. 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. A: Version B: Source connection ID C: Destination connection ID D: More than one of the above E: All of the above 9 43. 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), which arrive(s) at time t2. 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? A: t0 B: t1 C: t2 D: t3 E: It is impossible to say. 44. 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), which arrive(s) at time t2. 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? A: t0 B: t1 C: t2 D: t3 E: None of the above 45. 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), which arrive(s) at time t2. 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? A: t0 B: t1 C: t2 D: t3 E: None of the above 10