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

What does DNS do?

  1. AAssigns IP addresses to devices automatically
  2. BEncrypts web traffic
  3. CRoutes packets between networks
  4. DTranslates domain names into IP addresses
2.Easy

What does a packet header mainly contain?

  1. AThe user's actual file contents, split into equal-sized pieces
  2. BThe website's text and images
  3. CThe cable type used for the link
  4. DControl information such as source and destination addresses
3.Easy

Which protocol gives secure, encrypted remote login to another computer?

  1. ATelnet
  2. BFTP
  3. CSNMP
  4. DSSH
4.Medium

What is the purpose of the TCP three-way handshake?

  1. ATo encrypt the data
  2. BTo find the IP address of a host before data can be sent to it
  3. CTo close a connection quickly
  4. DTo establish a connection and synchronise sequence numbers
5.Medium

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

  1. A0.125 ms
  2. B12 ms
  3. C8 ms
  4. D1 ms
6.Medium

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

  1. A1024–49151
  2. B0–1023
  3. C49152–65535
  4. D0–65535
7.Hard

A firewall blocks all ICMP. Small web requests work, but large downloads over some paths hang. What is the likely cause?

  1. APath MTU discovery fails because "fragmentation needed" messages are blocked
  2. BTLS certificates are sent over ICMP
  3. CTCP cannot open connections without ICMP
  4. DDNS needs ICMP to resolve names
8.Hard

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

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

Answer key

  1. 1. D · Translates domain names into IP addresses
  2. 2. D · Control information such as source and destination addresses
  3. 3. D · SSH
  4. 4. D · To establish a connection and synchronise sequence numbers
  5. 5. D · 1 ms
  6. 6. B · 0–1023
  7. 7. A · Path MTU discovery fails because "fragmentation needed" messages are blocked
  8. 8. B · Victims send traffic for the gateway to the attacker, enabling a man-in-the-middle attack

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