Module 5: Practice Quiz

Question 1

What functions of a traditional router are implemented in hardware?

Answer 1

Data plane functions

The data plane is responsible for the actual movement of packets through the router.

Question 2

What functions of a traditional router are implemented in software?

Answer 2

Control plane functions

The control plane is responsible for routing decisions and managing the network.

Question 3

Which plane operates on the shorter timescale?

Answer 3

Data

The data plane operates at a faster level, handling packet forwarding in real-time.

Question 4

Classify the function: Computing paths based on a protocol.

Answer 4

Control Plane

This function involves determining the best routes for data transmission.

Question 5

Classify the function: Forwarding packets at Layer 3.

Answer 5

Data Plane

Layer 3 forwarding involves routing packets based on IP addresses.

Question 6

Classify the function: Switching packets at Layer 2.

Answer 6

Data Plane

Layer 2 switching involves moving frames based on MAC addresses.

Question 7

Classify the function: Running protocols to build a routing table.

Answer 7

Control Plane

This process includes the use of routing algorithms to update the routing table.

Question 8

Classify the function: Running the Spanning Tree protocol.

Answer 8

Control Plane

This protocol prevents loops in network topologies.

Question 9

Classify the function: Decrementing Time To Live (TTL).

Answer 9

Data Plane

TTL is a mechanism to limit the lifespan of packets in a network.

Question 10

Classify the function: Computing an IP header checksum.

Answer 10

Data Plane

This function ensures data integrity within the IP header.

Question 11

Classify the function: Running a protocol/logic to configure a middle box device for load balancing.

Answer 11

Control Plane

This involves managing traffic distribution across servers.

Question 12

Classify the function: Forwarding packets according to installed rules in a middlebox device.

Answer 12

Data Plane

This task deals with the real-time processing of packets.

Question 13

Which types of switching can send multiple packets across the fabric in parallel?

Answer 13

Interconnection Network / Crossbar

Crossbar switches allow simultaneous transmission of multiple packets.

Question 14

Determine the output link for the packet 11100001 10000000 0001 0001 0111 1001.

| Prefix Match | Output Link |

———— | ———– |
| 101* | A |
| 111* | B |
| 1100 1* | C |
| otherwise | D |

Answer 14

B

The longest prefix match is found for the destination IP.

Question 15

Determine the output link for the packet 1111 0001 1111 0000 1010 0001 0111 0111.

Prefix Match | Output Link |
| ———— | ———– |
| 101* | A |
| 111* | B |
| 1100 1* | C |
| otherwise | D |

Answer 15

B

The matching prefix leads to output link B.

Question 16

Determine the output link for the packet 1010 1010 1010 1010 1010 1010 1010 1010.

Prefix Match | Output Link |
| ———— | ———– |
| 101* | A |
| 111* | B |
| 1100 1* | C |
| otherwise | D |

Answer 16

A

The longest prefix match is found for output link A.

Question 17

Determine the output link for the packet 1100 1001 1000 0000 0001 0001 0111 0111.

Prefix Match | Output Link |
| ———— | ———– |
| 101* | A |
| 111* | B |
| 1100 1* | C |
| otherwise | D |

Answer 17

C

The matching prefix directs to output link C.

Question 18

Determine the mask for the address 192.168.0.1/24.

Answer 18

255.255.255.0

This mask indicates a subnet with 256 addresses.

Question 19

What node do we return for the prefix 0*?

Answer 19

a

Node ‘a’ corresponds to the prefix 0*.

Question 20

What node do we return for the prefix 1*?

Answer 20

b

Node ‘b’ corresponds to the prefix 1*.

Question 21

What node do we return for the prefix 01*?

Answer 21

c

Node ‘c’ corresponds to the prefix 01*.

Question 22

What node do we return for the prefix 00*?

Answer 22

a

Node ‘a’ is also associated with the prefix 00*.

Question 23

What node do we return for the prefix 0000*?

Answer 23

e

Node ‘e’ corresponds to the prefix 0000*.

Question 24

What node do we return for the prefix 00011*?

Answer 24

h

Node ‘h’ corresponds to the prefix 00011*.

Question 25

Consider the following prefix database.   ``` P1   =>   101*  P2   =>   0*  P3   =>   1*  P4   =>   10101*   ``` Consider expanding each prefix with stride length 3, so that we construct a fixed length multibit trie.  Which of the following prefixes are associated with P3? Select all that apply.    - 110* - 10* - 100* - 101* - 001* - 011* - 111*

Answer 25

110* 100* 111* ## Footnote P3 corresponds to prefixes starting with 1.

Question 26

What is the relationship between multibit tries and unibit tries?

Answer 26

A multibit trie is shorter than a unibit trie and requires fewer memory accesses to perform a lookup. ## Footnote This efficiency is due to the multibit trie storing multiple bits per node.

Question 27

Fixed-length multibit tries can support an arbitrary number of prefix lengths. | True/False

Answer 27

False ## Footnote The prefix set must match the lengths allowed by the multibit trie structure.