Introduction

Computing in general, and networking in particular, must deal with the issues relating to constrained resources. For computers, operating systems must find a way to equitably distribute the CPU time and memory among the various programs running on the computer. When the need for memory exceeds the available memory, the CPU spends more time performing memory management, moving data from memory to permanent storage, typically on a hard disk. Of course, the computer might be low on CPU resources at the same time, meaning the CPU has less available time to devote to overhead tasks like memory management. With only a small load on the computer, all is well. When the load exceeds the capacity of the CPU, memory, and other resources, a lower volume of useful work is accomplished, and the users get worse response time from the computer.

The competition for bandwidth is the classic battle for resources in networking. If the offered load sent into the network exceeds the available bandwidth, the network must react by either discarding packets, or queuing them in memory waiting for the bandwidth to become available. The packets that are queued experience more delay in the network than do packets that happen to be sent when the network is not congested. When consecutive packets experience different amounts of delay, variable delay, or jitter, has occurred. So, although bandwidth might be the constrained resource for which many network attached devices compete, other side effects—delay, jitter, and loss—occur as a result.

Cisco calls the general topic of how to manipulate bandwidth, delay, jitter, and loss characteristics in a network quality of service, or QoS. The Cisco QOS exam 642-642 tests your knowldege of QoS features and configurations covered in the course “Implementing Cisco Quality of Service (QOS).” This book covers the topics on the QOS exam, with some additional detailed explanations beyond what you find in the QOS course. By going deeper, you can approach the exam with more confidence, while learning valuable information that will help you deploy QoS in real networks. This book also attempts to cover the same breadth of topics found in the QOS course and exam, so it will keep you focused on what’s on the exam.

In years past, Cisco actually had two QoS courses, and exams based on each course. With the availability of the QOS 642-642 exam, and the course of the same name, Cisco converged the two courses into a single course.

This introduction discusses the QOS exam, including the exam topics covered, and some reasons why you might be interested in the exam.

Why Should I Take the QOS Exam?

Most people that take the QOS exam do so for one of three reasons:

Image   The Cisco Channel Partner Specialization Program

Image   The Cisco Qualified Specialist Program

Image   The Cisco Career Certification Program

The next few sections provide an explanation for each of these programs and how the QOS 642-642 exam relates.

The Cisco Channel Partner Specialization Program

The most popular reason for taking the QOS exam relates to the Cisco Channel Partner Specialization Program. Cisco calls their resellers and services partners Channel Partners. The way the program works is that Cisco moves more than 90 percent of its product sales, in dollar volumes, through its Channel Partners. So, Cisco is motivated to help themselves by working well with its Channel Partner community.

Cisco also focuses heavily on customer satisfaction. So, Cisco uses both a carrot and a stick to motivate Channel Partners to certify their employees with different technology specializations, which helps ensure that the Channel Partner engineers know what they are doing for the Cisco customers. For instance, to become a Gold partner, you need a certain number of points. To get the points, you need a certain number of technology specializations. To get the specializations, you need a particular mix of employees to certify in different roles—for instance, one role might be as a presales engineer, and another as a help desk customer service representative. To certify for a particular role, that employee must pass one or more certification exams, depending on the role.

Can the different Cisco Channel Partner roles, specializations, exams, and so on, become confusing? Sure. Suffice it to say that Channel Partners want to get the points needed to reach the next level of partnership with Cisco (Premier, Silver, and Gold, in order). Even if a Channel Partner does not want to make the next level of partnership with Cisco, it can use the fact that it has additional Channel Partner Technology Specializations when trying to win business.

At press time, Cisco had two active partner specializations that required the QOS exam. The two specializations are “Cisco IP Telephony Services” and “Cisco IP Communications Express.” The first is related to a wide range of skills with Cisco IP Telephony, and the latter is related more specifically to Cisco CallManager Express.

In order for a company to achieve a particular specialization, it must have a specified number of individuals who have passed a set of exams. A person who has passed one of the sets of exams is considered to be able to serve in a particular job role. For instance, for the Cisco IP Telephony Services Specialization, one of the job roles is “Cisco IP Telephony Design Specialist.” In order for a Cisco partner to qualify for this specialization, at least one employee must meet the job role. To meet the job role, that employee must have passed three exams, one of which is the QOS exam.

To see the larger picture, imagine a partner wanted to sell and service the Cisco IP Telephony products. By getting the Cisco IP Telephony Services Specialization, the Cisco partners can work more closely with Cisco and provide reassurance of their credential legitimacy to their customers.

In order to get the Specialization, a Cisco Channel Partner must meet the job role requirements in Table I-1.

Table I-1 IP Telephony Services Specialization: Roles and Requirements

Image

* More advanced certifications can be subsituted. For instance, the person can be CCNP instead of CCDA, or CCIE instead of CCNP.

As you can see from Table I-1, a Partner must have two employees each meet the “Design Engineer (Data)” and “Field Engineer” job roles as part of meeting the requirements for the specialization. As part of meeting those job roles, the Partner would need four different employees to pass the QoS exam, as well as several others listed in the table.

Cisco also has a “Cisco IP Communications Express” Specialization, which focuses more on issues relating to the Cisco CallManager Express product. Table I-2 lists the job roles and requirements.

Table I-2 IP Communications Express Specialization: Roles and Requirements

Image

* More advanced certifications can be subsituted. For instance, the person can be CCNP instead of CCDA, or CCIE instead of CCNP.

In short, if you work for a Channel Partner, and you design, sell, or implement IP Telephony solutions, you will most likely be asked to certify in one of the job roles listed in the table. And because several job roles for the IP Telephony Specializations require the QOS exam, the chances are you will need to pass this exam.

Cisco Focused Certification

For any networker in any networking job, it helps to have knowledge and skills. Networkers can benefit from having “proof” that they know a set of technologies. Having the right certification on your resume can help you land a job, both at another firm and inside the same company. For those networkers who work with customers and clients, having the right credentials, in the form of certifications, can help convince the salesman to convince the customer to hire your company for the consulting job.

Cisco offers a wide range of certifications, including a series of certifications in the Cisco Focused Certification program. Cisco focused certifications focus on one particular technology area, requiring multiple exams from that technology area to obtain a particular certification credential. The goal of the CQS certifications is to let people prove their knowledge and skill about a particular technology, as compared to the Cisco Career Certifications, which cover a broad range of topics.

Four different Cisco focused certifications require the QOS exam. Unsurprisingly, these four Cisco Focused Certifications all focus on IP telephony. Table I-3 lists the certifications, along with the required exams.

Table I-3 Cisco Qualified Specialist Certifications Requiring the QoS Exam

Image

* More advanced certifications can be subsituted. For instance, the person can be CCNP instead of CCDA, or CCIE instead of CCNP.

The QOS exam is the only exam required for all four of Cisco’s IP Telephony-related CQS certifications. With the requirement for the QOS exam for the technical roles in the Cisco Channel Partner IP Telephony Technology Specialization, pretty much anyone working with IP Telephony or voice over IP (VoIP) will need to take the exam, assuming that they want to be certified.

You might have noticed that the Cisco focused certifications exam requirements are very similar to the Channel Partner roles. In fact, the Cisco focused certifications requirements from Table I-3 are a subset of the requirements for a comparable Channel Partner certifications listed in Tables I-1 and I-2. Cisco has stated that, over time, the Partner Specialization job role requirements will meld with the Cisco focused certifications requirements, so that the requirements for a job role are essentially defined by a Cisco focused certifications specialization.

For more information on the Cisco Channel Partner Technology Specializations, and the Cisco Focused Certification program, refer to http://www.cisco.com/go/partner.

Cisco Certified Internetwork Professional (CCIP)

The Cisco primary certifcations fall under a program called the Cisco Career Certifications Program. That’s the Cisco program that implements its most popular certifications, including Cisco Certified Network Associate (CCNA), Cisco Certified Network Professional (CCNP), and Cisco Certified Internetwork Expert (CCIE).

Over the years, Cisco has added several additional Professional level certifications. Originally, Cisco offered CCNP, which required a skill level between the basic CCNA and the advanced CCIE Routing/Switching certification. Now, Cisco offers the Cisco Certified Design Professional (CCDP), Cisco Certified Security Professional (CCSP), and Cisco Certified Internetwork Professional (CCIP) certifications.

The QOS exam is part of the CCIP certification. The exams required for the CCIP certificataion (at press time) are as follows:

Image   Building Scalable Cisco Internetworks (BSCI) - 642-801 BSCI

Image   Implementing Cisco Quality of Service (QOS) - 642-642 QOS

Image   Configuring BGP on Cisco Routers (BGP) - 642-661 BGP

Image   Implementing Cisco MPLS (MPLS) - 642-611 MPLS

So what are the main motivations to get the CCIP certification? Well, the most obvious reason is to build your resume. Also, Cisco occasionally permits you to substitute CCIP instead of CCNP as the prerequisite for some certifications. Also, the Cisco Partner Specializataions sometimes require CCIP or allow CCIP to be substituted for another certification.

The overwhelming number of people who take the QOS exam do so in order to meet a job role requirement when working for a Cisco Partner. However, individuals also benefit with a more well-rounded resume, even if no job requirements exist.

Implementing the Cisco QOS Exam 642-642

The QOS exam consists of a 90 minute exam administered at a proctored exam facility affiliated either with VUE (http://www.vue.com) or Prometric (http://www.2test.com). The exam typically includes approximately 45-55 questions. (And of course, the time and the number of questions can certainly change at a later date, so do check cisco.com for the latest information.)

Cisco lists the topics covered in the QOS exam on its website; the list is repeated here. Like many Cisco exams, the QOS exam covers the topics in the Cisco QOS course, so those of you taking the QOS course from a Cisco Learning Partner, or a Cisco sponsered organization, will get some direct help in passing the exam.

Note   The time allowed for the exam, the number of questions, and even the exam topics covered can change, without a change to the exam number. So, do check cisco.com for the latest information.

The exam topics are as follows:

IP QoS Fundamentals

Image   Given a description of a converged network, identify problems that could lead to poor quality of service and explain how the problems might be resolved

Image   Define the term Quality of Service (QoS) and identify and explain the key steps to implementing QoS on a converged network

IP QoS Components

Image   List and explain the models for providing Quality of Service on a network

Image   Explain the purpose and function of the DiffServ model

Image   Describe the basic format of and explain the purpose of the DSCP field in the IP header

Image   Define and explain the different per hop behaviors used in DSCP

Image   Explain the interoperability between DSCP-based and IP-precedence-based devices in a network

Image   Given a list of QoS actions, correctly match the QoS actions to mechanisms for implementing QoS and identify where in a network the different QoS mechanisms are commonly used

Modular QoS CLI and Auto-QoS

Image   Given a network requiring QoS, explain how to implement a QoS policy using MQC

Image   Explain how AutoQoS is used to implement QoS policy

Classification and Marking

Image   Explain how link layer and network layer markings are used to define service classes and the different applications represented by each of these service classes

Image   Given a network and a description of QoS issues, use MQC CLI commands to classify packets

Image   Given a network and a description of QoS issues, use class-based marking to assign packets to a specific service class

Image   Describe the function of Network Based Application Recognition

Image   Describe the purpose of pre-classification to support QoS in various VPN (IPSEC, GRE, L2TP) configurations

Image   Describe QoS trust boundaries and their significance in LAN based classification and marking

Image   Identify the different classification and marking options available on Cisco L2 and L3 switching platforms

Congestion Management Methods

Image   List and explain the different queuing algorithms

Image   Explain the components of hardware and software queuing systems on Cisco routers and how they are effected by tuning and congestion

Image   Describe the benefits and drawbacks of using WFQ to implement QoS

Image   Explain the purpose and features of Class-Based WFQ (CBWFQ)

Image   Explain the purpose and features of Low Latency Queuing (LLQ)

Image   Identify the Cisco IOS commands required to configure and monitor LLQ on a Cisco router

Image   Describe and explain the different queuing capabilities available on the Cisco Catalyst 2950 Switch

Congestion Avoidance Methods

Image   Describe the drawbacks of tail drop as a congestion control mechanism

Image   Describe the elements of a RED traffic profile

Image   Describe Weighted Random Early Detection and how it can be used to prevent congestion

Image   Identify the Cisco IOS commands required to configure and monitor DSCP-based CB-WRED

Image   Explain how ECN interacts with WRED in Cisco IOS

Traffic Policing and Shaping

Image   Describe the purpose of traffic conditioning using traffic policing and traffic shaping and differentiate between the features of each

Image   Explain how network devices measure traffic rates using single rate or dual rate, single or dual token bucket mathematical models

Image   Identify the Cisco IOS commands required to configure and monitor single rate and dual rate CB-Policing

Image   Identify the Cisco IOS commands required to configure and monitor percentage based CB-Policing

Image   Explain how the two rate limits, average rate and peak rate, can be used to rate limit traffic

Image   Identify the Cisco IOS commands required to configure and monitor CB-Shaping

Image   Identify the Cisco IOS commands required to configure and monitor Frame Relay adaptive CB-Shaping on Frame Relay interfaces

Link Efficiency Mechanisms

Image   Explain the various link efficiency mechanisms and their function

Image   Identify the Cisco IOS commands required to configure and monitor CB header compression

Image   Given a list of link speeds and a specific delay requirement, determine the proper fragment size to use at each link speed and identify the typical delay requirement for VoIP packets

Image   Identify the Cisco IOS commands required to configure and monitor Multilink PPP with Interleaving

Image   Identify the Cisco IOS commands required to configure and monitor FRF.12

QoS Best Practices

Image   Explain the QoS requirements of the different application types

Image   List typical enterprise traffic classes then identify the delay, jitter, packet loss and bandwidth requirements of each traffic class

Image   Explain the best practice QoS implementations and configurations within the campus LAN

Image   Explain the best practice QoS implementations and configurations on the WAN customer edge (CE) and provider edge (PE) routers

Note   The list of objectives was taken from the Cisco website at http://www.cisco.com/warp/public/10/wwtraining/certprog/testing/current_exams/642-642.html.

Interpreting the QOS Exam Topics

The exam topics, like most exam topics listed by Cisco for other exams, use action words that follow a quasistandard called “Bloom’s Taxonomy of the Cognitive Domain.” Bloom’s taxonomy defines a standard for word usage for when educators create objectives for courses. Objectives written according to Bloom’s Taxonomy define what the learner should be able to accomplish after taking the class.

So, when you look at an exam topic, look for the action word. If you want to see a description of Bloom’s Taxonomy, search the Internet, and you will find a lot of matches. My favorite quick list of terms is at http://chiron.valdosta.edu/whuitt/col/cogsys/bloom.html. The action word in the exam topic gives you a good hint about the level of knowledge and skill you need to have before taking the exam. For instance, a course objective that uses the word “list” as the action word means that you should be able to list the features, but an action word such as “configure” means you should know all the related configuration commands, and how to use them. “Troubleshoot” might mean that you need to know what all the show and debug commands do for a particular topic.

For a speicific example, under the section about Traffic Policing and Shaping, the last exam topic says “Identify the Cisco IOS commands required to configure and monitor Frame Relay adaptive CB-Shaping on Frame Relay interfaces.” So, you had better know the configuration for adaptive CB-Shaping, and not just the concepts.

What does Bloom’s Taxonomy mean in terms of how you study for the exam? It means that you should focus on the action words in the exam topics, and make sure you can do those things for the stated topics. In a perfect world, the exam questions would also follow the same convention. However, some questions will slip through. However, when you are trying to determine your strategy for studying, and you are choosing the topics to focus on, or the basic topics, you should definitely interpret the meaning of the exam topics.

In addition, Cisco states that the posted exam topics for all its certification exams are guidelines. Cisco makes the effort to store their questions in an exam databases within the confines of the stated exam objectives, but doing this for every question and every exam is difficult. Thus, you could see questions that both fall outside the scope, and the depth, implied by the exam topics. However, if you follow the Cisco exam topic “guidelines,” you should have a good understanding of the breadth and depth of topics on the exam.

About the QOS 642-642 Exam Certification Guide

This section provides a brief insight into the contents of the book and the major goals, as well as some of the book features that you will encounter when using this book.

Goals of This Book

Unquestionably, the primary goal for this book is to help you pass the QOS certification exam. However, the means by which that goal is accomplished follows the Cisco Press Exam Certification Guide philosophy, which makes a statement about helping a reader pass the test through a deeper understanding of the material, as opposed to simply helping the reader memorize the answers to multiple-choice questions.

To accomplish this goal, the book’s main chapters cover all the topics on the QOS exam, plus an occasional mention of topics outside the scope of the exam just to make a key point. The depth of the conceptual coverage exceeds the depth of coverage in the QOS course. By doing so, you should be able to pass the exam with greater confidence.

A secondary goal for this book is to help you prepare for the CCIE Routing/Switching and CCIE Voice exams. Although this goal wasn’t actually intended when we wrote the first edition of this book, it turns out that a lot of people found the book useful for CCIE preparation as well. However, this second edition actually covers a narrower range of topics. Because CCIE covers a broad range of QoS topics, we kept some materials from earlier editions of the book and placed them in appendixes on the CD-ROM so that people working toward CCIE can still have the materials available.

The third goal is not so obvious. While written to help you pass the exams, it is our hope that this book will also be useful to anyone who needs to deploy QoS tools using Cisco gear. We hope that if you take the exam, you will keep this book as a desk reference, and for those of you who don’t take the exam, we hope you find this book a useful tool for delving into the details and really understanding QoS.

After teaching the DQOS course for the last couple of years, and after hearing students continually ask where they could read more on QoS topics, it became apparent that there were few good options available. This book fills that gap and provides a comprehensive reference for Cisco QoS.

Book Organization

This book contains 10 core chapters with titles that are comparable to the major headings listed in the QOS exam topics. For QOS exam candidates, you can simply dive into Chapter 1 and read through Chapter 10.

Chapters 13 cover most of the core background information needed to understand the different classes of Cisco QoS tools.

Chapters 48 each cover a different major type of QoS tool, covering the concepts, as well as the configuration of the tools.

Chapter 9 specifically addresses QoS issues on LAN switches to a depth and breadth appropriate to the exam.

Finally, Chapter 10 covers information about QoS best practices as described in the QoS course materials. As always, make sure you check www.cisco.com for the latest news about any future changes to the exam.

Appendix A provides the answers to the “Do I Know This Already?” Quizzes and Q&A sections found in Chapters 110.

Additionally, you can find Appendix B, “Additional QoS Reference Materials,” Appendix C, “Voice Call Admission Control Reference,” and Appendix D, “LAN QoS Reference” on the CD-ROM accompanying this book. These CD-only appendixes are designed to supplement what you definitely need to know for the QOS exam with some topic area coverage that you should know as a CCIP candidate.

Following is a description of each chapter’s coverage:

Image   Chapter 1, “QoS Overview

     QoS affects the characteristics of network traffic. To understand the QoS concepts and configurations discussed in other chapters, you must know what can be manipulated – namely, bandwidth, delay, jitter, and packet loss. Also, different types of traffic have different needs for bandwidth, delay, jitter and loss. Chapter 1 defines QoS terms, explains the concepts relating to bandwidth, delay, jitter, and packet loss, and identifies the traffic characteristcs of data, voice, and video traffic.

Image   Chapter 2, “QoS Tools and Architectures

     Cisco provides a large number of QoS tools inside the router IOS. One of the biggest challenges when preparing for either exam is remembering all the tools and keeping track of which tools provide what features. Chapter 2 begins by listing and describing the classes of tools, and then also listing the tools themselves. The remaining chapters delve into more depth on each particular class of tool.

     QoS tools typically either follow one of two QoS architectural philosophies. The two archtectures are called Differentiated Services and Integrated Services. The second part of this chapter explains the two architectures.

Image   Chapter 3, “MQC, QPM, and AutoQoS

     Many of the best QoS tools in IOS today use a set of CLI commands called the Modular QoS CLI, or MQC. This chapter begins by explaining MQC and showing how MQC commands can be used to configure QOS.

     The other major topic in this chapter is AutoQoS, which automatically configures QoS features according to the Cisco best practices for QoS in a network with VoIP traffic. Along the way, a few related, minor topics are covered, such as QPM.

Image   Chapter 4, “Classification and Marking

     Classification and Marking defines how a networking device can identify a particular packet and change some bits in the frame or packet header. The changed bits “mark” the packet, so other QoS tools can react to the marked field. This chapter covers the concepts, as well as five different classification and marking tools.

Image   Chapter 5, “Congestion Management

     Queuing tools on routers manage packets while they are waiting to exit an interface. This chapter discusses the general concepts of queuing in Cisco routers, and then covers the concepts and configuration behind a large variety of queuing tools. The Cisco DQOS exam topics refer to Queuing as “Congestion Management.”

Image   Chapter 6, “Traffic Shaping and Policing”

     Policing tools discard traffic that exceeds a particular rate. Shaping tools delay traffic so that, over time, the traffic rate does not exceed a particular rate. Both classes of tools use a concept of measuring the rate of sending or receiving bits. This chapter covers the general concepts of policing and shaping in Cisco routers, followed by the detailed concepts and configuration for two policing tools and four shaping tools.

Image   Chapter 7, “Congestion Avoidance Through Drop Policies

     Interestingly, statistics show that the biggest reason that packets are lost in networks is because a queue fills, leaving no room to hold another packet, forcing the device to discard the packet. Congestion Avoidance tools monitor queue depths, discarding some packets before the queue fills. The early discards cause the computers that sent the dropped packets to slow down the rate of sending packets, abating the congestion. As usual, this chapter covers the concepts and then the configuration behind two congestion avoidance tools.

Image   Chapter 8, “Link Efficiency Tools

     Link Efficiency tools deal with how to best use the bandwidth on a link between two routers. Compression, which is one class of link efficiency tool, reduces the required bandwidth. Fragmentation tools reduce delay for small, delay-sensitive packets by breaking large packets into smaller packets. The smaller delay-sensitive packets can be sent before the fragments of the original larger packet. This chapter covers the base concepts as well as the configuration details.

Image   Chapter 9, “LAN QoS

     The QoS exam covers some specific tools for QoS on Cisco LAN switches. These topics are collected into a single chapter, with examples using 2950 Series switches.

Image   Chapter 10, “Cisco QoS Best Practices

     The Cisco QoS course covers a set of recommendations for QoS in the Enterprise, as well as for service providers. This chapter covers those details.

Image   Appendix A, “Answers to the ‘Do I Know This Already?’ Quizzes and Q&A Sections”

     This appendix lists the questions covered at the beginning and end of each chapter, as well as their answers.

Image   Appendix B, “Additional QoS Reference Materials” (found on the book’s accompanying CD-ROM)

     This appendix contains material from earlier editions of this book. A few topics might be useful as background information for your preparation for the exam, but the main purpose of the appendix is to list coverage of topics that could be on the CCIE exams. (These topics were not updated for this edition of the book and are available for reference with that caveat in mind.)

Image   Appendix C, “Voice Call Admission Control Reference” (found on the book’s accompanying CD-ROM)

     This appendix is a reprint of the DQOS Exam Certification Guide’s chapter on Voice Call Admission Control. Voice CAC is no longer on the QoS exam; it is included on the CD-ROM for reference for anyone interested in Voice CAC. (These topics were not updated for this edition of the book and are available for reference with that caveat in mind.)

Image   Appendix D, “LAN QoS Reference” (found on the book’s accompanying CD-ROM)

     This appendix is a reprint of the DQOS Exam Certification Guide’s chapter on LAN QoS. The current QoS exam covers different topics on LAN QoS, with specific focus on the QoS commands on the 2950 Series switches. This appendix contains a broader coverage of LAN QoS, and some samples and comparisons of QoS on different Cisco switches. (These topics were not updated for this edition of the book and are available for reference with that caveat in mind.)

Book Features

The core chapters of this book have several features that help you make the best use of your time:

Image   “Do I Know This Already?” Quizes—Each chapter begins with a quiz that helps you determine the amount of time you need to spend studying that chapter. If you follow the directions at the beginning of the chapter, the “Do I Know This Already?” quiz directs you to study all or particular parts of the chapter.

Image   Foundation Topics—These are the core sections of each chapter. They explain the protocols, concepts, and configuration for the topics in that chapter.

Image   Foundation Summary—Near the end of each chapter, a summary collects the most important tables and figures from the chapter. The “Foundation Summary” section is designed to help you review the key concepts in the chapter if you scored well on the “Do I Know This Already?” quiz. This section is also an excellent tool for last-minute reviews before you take the exam.

Image   Q&A—Each chapter ends with a Q&A section that forces you to exercise your recall of the facts and processes described in the chapter’s foundation topics. The questions are generally harder than the actual exam, partly because the questions are in “short answer” format, instead of multiple choice format. These questions are a great way to increase the accuracy of your recollection of the facts and to practice for taking the exam.

Image   Examples—Located inside the Foundation Topics of most chapters, the text includes screen captures from lab scenarios that show how each tool works. The examples include a topology, the configuration, and show command output that matches the examples.

Image   CD-based practice exam—The companion CD contains multiple-choice questions and a testing engine. As part of your final preparation, you should practice with these questions to help you get used to the exam-taking process, as well as help refine and prove your knowledge of the exam topics.

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