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Chapter 5: Domain 4: Communication and Network Security

  1. Which protocol should be used for an audio streaming server, where some loss is acceptable?
    A. IP
    B. ICMP
    C. TCP
    D. UDP

Correct Answer and Explanation: D. Answer D is correct; UDP is used for high-speed applications that can handle some loss.

Incorrect Answers and Explanations: A, B, and C. Answers A, B, and C are incorrect. IP is a carrier protocol, which would require a higher-layer protocol such as UDP to support an application. ICMP is a helper protocol, and does not carry application data. TCP is a reliable and slow protocol, not the best choice when speed is required, and loss is OK.

  1. What network technology uses fixed-length cells to carry data?
    A. ARCNET
    B. ATM
    C. Ethernet
    D. FDDI

Correct Answer and Explanation: B. Answer B is correct; ATM is a networking technology that uses 53-byte fixed-length cells.

Incorrect Answers and Explanations: A, C, and D. Answers A, C, and D are incorrect. ARCNET passes tokens. Ethernet uses frames. FDDI also uses tokens.

  1. Secure Shell (SSH) servers listen on what port and protocol?
    A. TCP port 20
    B. TCP port 21
    C. TCP port 22
    D. TCP port 23

Correct Answer and Explanation: C. Answer C is correct; SSH servers listen on TCP port 22.

Incorrect Answers and Explanations: A, B, and D. Answers A, B, and D are incorrect. FTP uses TCP ports 20 and 21. Telnet uses TCP port 23.

  1. What network cable type can transmit the most data at the longest distance?
    A. Coaxial
    B. Fiber Optic
    C. Shielded Twisted Pair (STP)
    D. Unshielded Twisted Pair (UTP)

Correct Answer and Explanation: B. Answer B is correct; Fiber Optic Network Cable can transmit the most data the furthest.

Incorrect Answers and Explanations: A, C, and D. Answers A, C, and D are incorrect. Among the four answers, STP and UTP can transmit the shortest distance. Coaxial network cable can transmit more data further than twisted pair cabling, but not nearly as far as fiber.

  1. Which device operates at Layer 2 of the OSI model?
    A. Hub
    B. Firewall
    C. Switch
    D. Router

Correct Answer and Explanation: C. Answer C is correct; a switch operates at layer 2 (data link layer) of the OSI model.

Incorrect Answers and Explanations: A, B, and D. Answers A, B, and D are incorrect. A hub operates at layer 1 (physical). Packet filter and stateful firewalls operate at layers 3 and 4, Circuit-Level Proxies (such as SOCKS) operate up to layer 5 (session), and application-layer proxies operate up to layer 7 (application). Routers operate at layer 3 (network).