Advanced IP Addressing

1. VLSM allows you to summarize 192.168.2.0/24 and 192.168.3.0/24 as 192.168.2.0/25.

A. True

B. False

Answer: B

CIDR allows you to summarize class networks together; VLSM allows you to summarize subnets only back to the class network boundary.

2. VLSM allows a network segment to have more than one subnet mask.

A. True

B. False

Answer: B

Each segment has a single network number and mask. VLSM allows a class address, not a network segment, to have more than one subnet mask.

3. Which protocol supports VLSM?

A. RIP V2

B. IGRP

C. RIP and IGRP

D. None of these

Answer: A

RIPv2 supports VLSM (RIPv1 doesn’t).

B is classful and doesn’t support VLSM. C includes a classful protocol. There is a correct answer, so D is incorrect.

4. You are given a Class C network, 192.168.1.0/24. You need one network with 120 hosts and two networks with 60 hosts. How many subnet masks do you need?

A. 1

B. 2

C. 3

D. 4

Answer: B

You need two subnet masks: 255.255.255.128 (/25) and 255.255.255.192 (/26). This creates three networks, for instance, 192.168.1.0/25, 192.168.128/26, and 192.168.1.192/26.

5. You are given a class C network, 192.168.1.0/24. You need one network with 120 hosts and three networks with 60 hosts. What subnet mask values would you use?

A. 255.255.255.128 and 255.255.255.192

B. 255.255.255.128

C. 255.255.255.192

D. None of these

Answer: D

This is impossible with a single Class C network. One hundred twenty hosts require a 255.255.255.128 mask, which is half a Class C network. Sixty hosts require a 255.255.255.192 mask; however, you need three of these, which is 3/4 of a Class C network. Therefore it is impossible.

A is incorrect because it accommodates only the 120-host and two 60-host segments. B is incorrect because it accommodates only two subnets. C is incorrect because it accommodates the three 60-host segments, but not the 120-host segment.

6. You are given a class C network, 192.168.1.0/24. You need three networks with 60 hosts and two networks with 30 hosts. What are the subnet mask values you could use?

A. 255.255.255.128 and 255.255.255.192

B. 255.255.255.224 and 255.255.255.240

C. 255.255.255.192 and 255.255.255.224

D. None of these

Answer: A

A and C. A creates one 126-host segment and two 62-host segments. C creates three 62-host segments and two 30-host segments.

B’s second mask supports only 14 hosts. D is incorrect because there is a correct answer.

7. You are given this address space: 172.16.5.0/25. You need one network with 64 hosts and two with 30 hosts. What are the most specific subnet mask values to use?

A. /25 and /26

B. /26 and /27

C. /27 and /28

D. None of these

Answer: D

Sixty-four hosts require a 25-bit mask, and you are only given this to begin with—62 hosts would work with a 26-bit mask.

A, B, and C don’t support enough addresses.

8. You are given a class C network and you have four LAN segments with the following numbers of devices: 120, 60, and two with 30. What subnet mask values would you use to accommodate these segments?

A. /24, /25, and /26

B. /25, /26, and /27

C. /26, /27, and /28

D. None of these

Answer: B

A bit mask of 25 creates two networks: 0 and 128. If you take one of these subnets and apply a 26-bit mask, you have two more networks, such as 128 and 192. Taking one of these two subnets, applying a 27-bit mask creates two more subnets, such as 192 and 224.

A, C, and D don’t support enough addresses to accommodate all four LAN segments.

9. VLSM allows you to summarize __________ back to the class boundary.

A. Subnets

B. Networks

Answer: A

VLSM allows you to summarize subnets back to the class A, B, or C network boundary.

B is a non-subnetted address space and therefore is a Class A, B or C network number and can’t be summarized with VLSM, but can be with CIDR.

10. Which of the following is not an advantage of route summarization?

A. It requires less memory and processing.

B. It supports smaller routing update sizes.

C. It contains network problems.

D. It supports discontiguous subnets.

Answer: D

Discontiguous subnets are supported by classless protocols, but they are not an advantage of summarization. Actually, summarization is more difficult if you have discontiguous subnets.

A, B, and C are advantages of route summarization.

11. _________ allows you to create this summarization: 10.0.0.0/7.

A. Subnetting

B. CDR

C. Supernetting

D. VLSM

Answer: C

Supernetting, or CIDR, supports summarization of contiguous blocks of class A, B, or C networks.

A is the opposite of summarization. B should be CIDR, not CDR. D allows you to summarize subnets, not networks.

12. Which of the following are classless protocols?

A. IGRP

B. EIGRP

C. IGRP and EIGRP

D. Neither IGRP or EIGRP

Answer: B

EIGRP, as well as IS-IS, BGP, OSPF, and RIPv2, is a classless protocol.

A is not a classless protocol. C includes a classful protocol (IGRP). D is incorrect because there is a correct answer.

13. A routing protocol that supports route summarization must perform all except which of the following?

A. Carry the subnet mask with the network entry.

B. Make routing decisions based on the entire destination IP address.

C. Summarize entries so that the same lowest-order bits match.

D. None of these.

Answer: C

Summarized entries must have the same highest-order matching bits, not lowest.

A and B are things a routing protocol supporting route summarization must perform. D is incorrect because there is a correct answer.

14. You have the following two routes: 192.168.1.64/27 and 192.168.1.96/27. Enter the most specific summarized route for these two subnets: ___________.

A. IF YOU DUNNO THEN CLICK TO VIEW THE ANSWER

Answer: A

192.168.1.64/26 THIS INCULDES ADDRESSESS FROM 192.168.1.64 THROUGH 192.168.1.127

192.168.1.64/26: this includes addresses from 192.168.1.64 through 192.168.1.127.

15. You have the following four routes: 192.168.1.32/30, 192.168.1.36/30, 192.168.1.40/30, and 192.168.1.44/30. Enter the most specific summarized route for these four subnets: __________.

A. IF YOU DUNNO THEN CLICK TO VIEW THE ANSWER

Answer: A

192.168.1.32/28 THIS INCULDES ADDRESSES FROM 192.168.1.32 THROUGH 192.168.1.47

192.168.1.32/28: this includes addresses from 192.168.1.32 through 192.168.1.47.