This chapter covers the
following topics, which
you need to understand to
pass the CCNP/CCDP/CCIP
■ IP subnetting
■ Prefix routing/CIDR
■ Variable-length subnet masks
This chapter reviews some of the fundamental concepts of IP addressing. After mastering its subtleties, you will be able to consider the network management power that results from careful design of the IP addressing scheme.
The discussion of IP addressing is fundamental to the rest of the topics covered within this book and will directly reﬂect questions on the exam. If you do not thoroughly understand the contents of this chapter, it is safe to say that it will be impossible to pass the exam. The entire BSCI exam is based on IP addressing. For this reason, IP addressing is reviewed thoroughly in this book.
“Do I Know This Already?” Quiz
The purpose of the “Do I Know This Already?” quiz is to help you decide what parts of this chapter to use. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now.
The 12-question quiz, derived from the major sections in the “Foundation Topics” portion of the chapter, helps you to determine how to spend your limited study time.
Table 2-1 outlines the major topics discussed in this chapter and the “Do I Know This Already?” quiz questions that correspond to those topics.
Table 2-1 “Do I Know This Already?” Foundation Topics Section-to-Question Mapping
NOTE: The goal of self-assessment is to gauge your mastery of the topics in this chapter. If you do not know the answer to a question or are only partially sure of the answer, you should mark this question wrong for purposes of the self-assessment. Giving yourself credit for an answer you correctly guess skews your self-assessment results and might provide you with a false sense of security.
1. You are given a Class C address with the requirement to accommodate 14 subnets, not including the zero address for the network or the broadcast address for the subnet. It is also necessary to have 10 hosts on each subnet. What subnet mask would you use?
a. 255.255.255.240 with a preﬁx of /28
b. 255.255.255.248, which is a preﬁx of /28
c. 0.0.0.15, which is a preﬁx mask of /28
d. 255.255.255.0, which is the network number which is no preﬁx mask
2. List the range of hosts available on the 126.96.36.199/28 subnet. Do not include the zero address or the broadcast address for the subnet.
3. Convert the subnet address 188.8.131.52/24 to binary notation.
4. What does CIDR stand for?
a. Classful Interdomain Resolution
b. Classless Intradomain Routing
c. Classless Interdomain Routing
d. Classful Interdomain Routing
5. From the following list, which is an advantage of preﬁx routing?
a. The routing tables in the Internet are smaller.
b. The routing tables within an autonomous system are smaller.
c. The Internet has to allocate fewer Class C addresses.
d. Preﬁx routing adds to the IP header, which speeds up the fast cache forwarding process.
6. The address 184.108.40.206/21 can be identiﬁed as which of the following?
a. A Class C address
b. A group of eight Class C networks summarized to one address
c. A Class B address subnetted to 5 bits, allowing 30 subnets
d. A mistake in subnetting
7. Which routing protocols support VLSM?
a. RIPv2, OSPF, IS-IS, EIGRP, BGP-4
b. RIPv2, OSPF, IS-IS, IGRP, EIGRP, BGP-4
c. RIPv2, OSPF, IS-IS, EIGRP
d. RIPv2, OSPF, EIGRP, BGP-4
8. What does VLSM stand for?
a. Various-length subnetting mask
b. Variable-length subnet mask
c. Very long sustained mantra
d. Variable-length subnet mechanism
9. Which of the following options best describes the difference between CIDR and VLSM?
a. CIDR is the technique for designing and allocating addresses, whereas VLSM deﬁnes the technology used by the routing protocol.
b. VLSM summarizes networks within the Internet.
c. There is no difference between these terms; they are interchangeable.
d. CIDR summarizes networks within the Internet as it is applied to blocks of classful net-works. VLSM is used within an autonomous system, as it is applied to a classful network.
10. The Class B network address of 220.127.116.11 has been given a mask of 255.255.255.0. The subnets 18.104.22.168, 22.214.171.124, 126.96.36.199, 188.8.131.52, 184.108.40.206, 220.127.116.11, 18.104.22.168, and 22.214.171.124 need to be summarized using VLSM. Give the subnet and new mask to achieve this summarization.
a. 126.96.36.199/21 with a mask 255.255.240.0
b. 188.8.131.52/20 with a mask 255.255.240.0
c. 184.108.40.206/21 with a mask 255.255.248.0
d. 220.127.116.11/20 with a mask 255.255.240.0
11. Given the mask 255.255.255.224 for the IP network 18.104.22.168, which of the following subnets are summarized within this address?
12. Manual summarization is available in which of the following interior routing protocols?
a. OSPF, RIPv1,IS-IS
b. EIGRP, OSPF, BGP-4
c. EIGRP, OSPF, RIPv2
d. EIGRP, IS-IS, RIPv2, OSPF
The answers to this quiz are found in Appendix A, “Answers to Chapter ‘Do I Know This Already?’ Quizzes and Q&A Sections.” The suggested choices for your next step are as follows:
■ 6 or less overall score —Read the entire chapter. This includes the “Foundation Topics” and “Foundation Summary” sections, the “Q&A” section, and the “Scenarios” at the end of the chapter.
■ 7 to 9 overall score —Begin with the “Foundation Summary” section, and then go to the “Q&A” section and the “Scenarios” at the end of the chapter. If you have trouble with these exercises, read the appropriate sections in “Foundation Topics.
■ 10 or more overall score —If you want more review on these topics, skip to the “Foundation Summary” section, and then go to the “Q&A” section and the “Scenarios” at the end of the chapter. Otherwise, move to the next chapter.