CCNA INTRO Exam Certification Guide - Part 5 Wide-Area Networking - Chapter 15

C H A P T E R15 Remote Access Technologies Earlier in this book, you learned about Ethernet LANs, point-to-point WAN links, and Frame Relay. All of these technologies can be used to connect a corporate site to the Internet. However, none of these options is cost-effective for connecting the typical home-based user to the Internet. In this chapter, you will learn about several different technologies used for Internet access from the home. Some of these same technologies can be used to remotely access corporate networks as well. This chapter covers the most common remote access technologies— namely, analog modems, DSL, ISDN, and cable. AUTHOR’S NOTE While they may be on the CCNA exam, the topics in this chapter are less likely to be on the CCNA exam than most other topics in this book. For those of you that are planning to take the CCNA exam, instead of taking both the INTRO and ICND exams, you might consider skipping this chapter. Refer to the introduction to this book for more perspectives on the CCNA exam topics. “Do I Know This Already?” Quiz The purpose of the “Do I Know This Already?” quiz is to help you decide whether you really need to read the entire chapter. If you already intend to read the entire chapter, you do not necessarily need to answer these questions now. The 15-question quiz, derived from the major sections in the “Foundation Topics” portion of the chapter, helps you determine how to spend your limited study time. 430 Chapter 15: Remote Access Technologies Table 15-1 outlines the major topics discussed in this chapter and the “Do I Know This Already?” quiz questions that correspond to those topics. Table 15-1 “Do I Know This Already?” Foundation Topics Section-to-Question Mapping Foundations Topics Section Perspectives on the PSTN Analog Modems ISDN DSL Cable Modems Comparisons of Remote Access Technologies Questions Covered in This Section 1—2 3—4 5—7 8—10 11—12 13—15 CAUTION 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 that you correctly guess skews your self-assessment results and might provide you with a false sense of security. 1. Which of the following acronyms identifies a voice codec used to encode analog voice signals into a 64-kbps digital data stream? a. PSTN b. MCNS c. ADSL d. PCM e. AS-CELP 2. How many DS0 channels are in a DS1 in the United States? a. 1 b. 2 c. 8 d. 16 e. 24 f. 28 g. 32 “Do I Know This Already?” Quiz 431 3. Which of the following best describes the function of demodulation by a modem? a. Encoding an incoming analog signal as a digital signal b. Decoding an incoming digital signal into an analog signal c. Encoding a set of binary digits as an analog electrical signal d. Decoding an incoming analog electrical signal into a set of binary digits e. Encoding a set of binary digits as a digital electrical signal f. Decoding an incoming digital electrical signal into a set of binary digits 4. Which of the following modem standards do not support 56-kbps speeds downstream? a. V.22 b. V.22bis c. V.42 d. V.90 e. V.92 f. V.32 g. V.32bis h. V.34 5. Which of the following terms best describes features of an ISDN PRI in Europe? a. B+D b. 2B+D c. 23B+D d. 24B+D e. 30B+D f. 31B+D g. 32B+D 432 Chapter 15: Remote Access Technologies 6. Imagine that you plug an analog phone into an ISDN modem and call a friend at her house, where she uses an analog phone using plain-old telephone service (POTS). At which of the following points in a network will a voice codec be used? a. Your friend’s telephone b. The phone switch into which your friend’s local line is connected c. The phone switch into which your ISDN BRI line is connected d. Your ISDN modem e. Your telephone 7. What does the letter B stand for in the ISDN term B channel? a. Bearer b. Broadband c. Binary d. Best 8. Which of the following DSL standards has a limit of 18,000 feet for the length of the local loop? a. IDSL b. DSL c. ADSL d. VDSL e. HDSL 9. Imagine a local phone line from a house to a local telco CO. When the customer at that house requests DSL service, what type of device does the telco move the CO end of the local line to? a. DSLAM b. DSL router c. DSL modem d. Class 5 switch e. Voice switch f. Head end “Do I Know This Already?” Quiz 433 10. Which of the following protocols are used by DSL modem and routers for data link layer functions? a. PPP b. IEEE 802.3 c. ATM d. IEEE 802.1Q e. MCNS MAC 11. Which of the following protocols is used by cable modems for data link layer functions? a. PPP b. IEEE 802.3 c. ATM d. IEEE 802.1Q e. MCNS MAC 12. Which of the following protocols are used by a cable modem for the upstream data? a. PCM b. QAM-16 c. QAM-64 d. QAM-256 e. QPSK 13. Which of the following remote access technologies uses ATM, Ethernet, and PPP as data-link protocols? a. Analog modems b. ISDN c. DSL d. Cable modems ... - tailieumienphi.vn