Computer networks worksheet with answers

In the client-server model:

1. AAll devices must be in the same room
2. BServers send requests and clients answer them
3. CEvery computer stores the whole internet
4. DClients send requests and a server provides the service

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

1. ASession layer
2. BPhysical layer
3. CData link layer
4. DNetwork layer

Which IEEE standard family defines Wi-Fi wireless LANs?

1. AIEEE 802.11
2. BIEEE 802.1Q
3. CIEEE 802.15
4. DIEEE 802.3

What characterises a distributed denial-of-service (DDoS) attack?

1. AAn attacker reads unencrypted Wi-Fi traffic from a nearby car
2. BA virus deletes files on a single PC
3. CMany compromised machines flood a target with traffic
4. DOne attacker guesses a user's password

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

How does a stateful firewall differ from a simple packet filter?

1. AIt blocks all incoming traffic without exceptions, including replies to outgoing requests
2. BIt encrypts every packet it forwards
3. CIt tracks connections and allows replies that belong to established sessions
4. DIt only checks the MAC address of each frame

Which of these addresses is a public (not RFC 1918 private) IPv4 address?

1. A192.168.255.1
2. B10.255.0.1
3. C172.31.0.1
4. D172.32.0.1

A student runs a game server on a PC behind a home NAT router. Friends on the internet cannot connect. What is the usual fix?

1. AChange the PC's subnet mask to /32
2. BConfigure port forwarding on the router to the PC's private address
3. CGive the PC a different MAC address so the router can find it from outside
4. DTurn off the PC's DNS client