Computer networks worksheet with answers

Free printable Computer networks worksheet: 8 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

What is the default port number for SSH?

  1. A53
  2. B23
  3. C110
  4. D22
2.Easy

Which type of network covers a large geographic area, such as a whole country?

  1. AA personal area network (PAN)
  2. BA wide area network (WAN)
  3. CA local area network (LAN)
  4. DA virtual LAN (VLAN)
3.Easy

Which device simply repeats every incoming signal out of all its other ports?

  1. AA firewall
  2. BA router
  3. CA hub
  4. DA switch
4.Medium

A router has routes for 10.0.0.0/8 and 10.1.0.0/16. Which route does it use for a packet to 10.1.5.5?

  1. A10.0.0.0/8, because it was added first
  2. B10.0.0.0/8, because it covers more addresses than the /16
  3. C10.1.0.0/16, because it is the longest matching prefix
  4. DBoth routes, splitting the traffic equally
5.Medium

Why does a switch sometimes send a frame out of all ports except the one it came in on?

  1. AThe destination MAC address is not yet in its address table
  2. BThe frame is too large for one port
  3. CThe frame has a wrong IP checksum and must be checked by every host
  4. DThe switch is acting as a router
6.Medium

Which range of TCP/UDP port numbers is reserved as "well-known" ports?

  1. A1024–49151
  2. B49152–65535
  3. C0–65535
  4. D0–1023
7.Hard

A PC can reach printers on its own subnet but nothing beyond it. Its IP address and mask are correct. What is the most likely fault?

  1. AA duplicate MAC address on the internet
  2. BA missing or wrong default gateway
  3. CThe TCP window is too small
  4. DA faulty DNS server setting
8.Hard

What is the main benefit of persistent connections (keep-alive) in HTTP/1.1?

  1. AThe server can push updates over UDP
  2. BResponses can arrive in any order on one stream, so slow replies do not block others
  3. CThe connection stays encrypted without TLS
  4. DSeveral requests reuse one TCP connection, avoiding repeated handshakes

Answer key

  1. 1. D · 22
  2. 2. B · A wide area network (WAN)
  3. 3. C · A hub
  4. 4. C · 10.1.0.0/16, because it is the longest matching prefix
  5. 5. A · The destination MAC address is not yet in its address table
  6. 6. D · 0–1023
  7. 7. B · A missing or wrong default gateway
  8. 8. D · Several requests reuse one TCP connection, avoiding repeated handshakes

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