Computer networks worksheet with answers

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

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

In networking, what does bandwidth usually refer to?

1. AThe delay before data arrives
2. BThe maximum data rate a link can carry
3. CThe share of packets that are lost
4. DThe number of hops to a destination

Which type of cable carries data as pulses of light?

1. ATwisted-pair cable
2. BShielded copper cable
3. CFibre-optic cable
4. DCoaxial cable

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

1. AEncrypting the frame
2. BCorrecting every bit error automatically
3. CChoosing the best route
4. DDetecting transmission errors

At which OSI layer does a switch normally operate?

1. ANetwork (layer 3)
2. BData link (layer 2)
3. CPhysical (layer 1)
4. DTransport (layer 4)

Why is UDP often preferred for live video calls?

1. ALow delay matters more than retransmitting every lost packet
2. BUDP encrypts data automatically
3. CUDP is required for all video
4. DUDP guarantees every packet arrives, so the picture never freezes

What does the Diffie-Hellman key exchange achieve on its own, and what is its weakness?

1. AIt agrees a shared secret over a public channel, but alone it is open to a man-in-the-middle
2. BIt signs certificates for websites, but only works with short keys
3. CIt encrypts bulk data directly over a public channel, but it is far too slow for large files and video
4. DIt authenticates both users with passwords, but needs a central server

Why does TCP choose an unpredictable initial sequence number for each connection?

1. ATo avoid confusion with old segments and make spoofed segments harder to inject
2. BTo select the best route to the destination for the segments of that connection
3. CTo encrypt the payload of each segment
4. DTo compress the data more efficiently