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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Name: ____________________   Date: ____________

1.Easy

Which OSI layer transmits raw bits as electrical, optical or radio signals?

  1. ASession layer
  2. BNetwork layer
  3. CData link layer
  4. DPhysical layer
2.Easy

A MAC address identifies:

  1. AA user account
  2. BA website
  3. CA router's public IP
  4. DA network interface on the local link
3.Easy

Which device forwards packets between different networks based on IP addresses?

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

Which IPv4 header field stops packets from circulating forever in a routing loop?

  1. AIdentification
  2. BType of service
  3. CHeader checksum
  4. DTime to live (TTL)
5.Medium

How long does it take to put a 1500-byte packet onto a 12 Mbit/s link (transmission delay)?

  1. A1 ms
  2. B8 ms
  3. C0.125 ms
  4. D12 ms
6.Medium

What is a cyclic redundancy check (CRC) used for in Ethernet frames?

  1. AChoosing the best route
  2. BEncrypting the frame
  3. CCorrecting every bit error automatically
  4. DDetecting transmission errors
7.Hard

An attacker on a LAN sends forged ARP replies claiming the gateway's IP address. What is the likely result?

  1. AThe gateway's IP address is permanently changed to the attacker's address on every router
  2. BAll DNS queries fail across the internet
  3. CThe switch shuts down all of its ports
  4. DVictims send traffic for the gateway to the attacker, enabling a man-in-the-middle attack
8.Hard

How does a content delivery network (CDN) mainly improve web performance?

  1. AIt serves cached content from servers close to the users
  2. BIt replaces TCP with a faster transport protocol
  3. CIt increases the bandwidth of the users' own home connections
  4. DIt removes the need for DNS lookups

Answer key

  1. 1. D · Physical layer
  2. 2. D · A network interface on the local link
  3. 3. D · A router
  4. 4. D · Time to live (TTL)
  5. 5. A · 1 ms
  6. 6. D · Detecting transmission errors
  7. 7. D · Victims send traffic for the gateway to the attacker, enabling a man-in-the-middle attack
  8. 8. A · It serves cached content from servers close to the users

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