Link Layer

Question 0

What link layer uses CSMA/CD?

Answer 0

Ethernet

Question 1

What does CSMA/CD stand for?

Answer 1

Carrier Sense, Multiple Access with Collision Detection

Question 2

How many bits are in an Ethernet address?

Answer 2

48-bits

Question 3

What is another name for the 48-bit hardware address?

Answer 3

MAC (Media Access Control) address.

Question 4

What two protocols map between the 48-bit physical address of a device and its IP Address?

Answer 4

ARP (Address Resolution Protocol) and RARP (Reverse Address Resolution Protocol)

Question 5

What five fields are contained in an Ethernet (RFC 894) frame?

Answer 5

Destination address, source address, type, data, CRC.

Question 6

What does CRC stand for?

Answer 6

Cyclic Redundancy Check

Question 7

What is the minimum size for the Ethernet (RFC 894) data section?

Answer 7

46 bytes

Question 8

What does PPP stand for?

Answer 8

Point-to-point protocol

Question 9

What Class A network ID is reserved for the loopback interface?

Answer 9

127

Question 10

By convention what IP address is used for the loopback address?

Answer 10

127.0.0.1

Question 11

What does MTU stand for?

Answer 11

Maximum Transmission Unit

Question 12

What type of network should a datagram addressed to the loopback address appear on?

Answer 12

None. Datagrams addressed to the loopback address should never appear on the network.

Question 13

What is the MTU for Ethernet?

Answer 13

1500 bytes

Question 14

What happens if the Internet layer has a datagram to send that is larger than the link layer’s MTU.

Answer 14

Fragmentation. The IP layer fragments the datagram before sending it to the link layer.

Question 15

When traveling across multiple networks, which networks’ MTU is used to determine the MTU for the connection?

Answer 15

The slowest.

Question 17

For a multi-network connection what is the maximum transmission unit called?

Answer 17

Path MTU