CCENT/CCNA ICND1 Official Exam Certification Guide - Chapter 16

WAN Concepts Chương 4, "nguyên tắc cơ bản của WAN", giới thiệu hai công nghệ quan trọng ngày hôm nay WAN phổ biến trong các mạng doanh nghiệp: Cho thuê đường dây, sử dụng điều khiển hoặc cấp cao liên kết dữ liệu (HDLC) hoặc điểm-toPoint Protocol (PPP) Frame Relay Phần IV của cuốn sách này bao gồm phần còn lại của chủ đề WAN cụ thể trong cuốn sách này. Đặc biệt, chương này xem xét một phạm vi rộng lớn hơn của công nghệ WAN, bao gồm cả các công nghệ truy cập thường sử dụng Internet. Chương 17, "Cấu...
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CCENT/CCNA ICND1 Official Exam Certification Guide - Chapter 16 1828xbook.fm Page 509 Thursday, July 26, 2007 3:10 PM Part IV: Wide-Area Networks Chapter 16 WAN Concepts Chapter 17 WAN Configuration 1828xbook.fm Page 510 Thursday, July 26, 2007 3:10 PM This chapter covers the following subjects: WAN Technologies: This section examines several additional WAN technologies that were not covered in Chapter 4, namely modems, DSL, cable, and ATM. IP Services for Internet Access: This section examines how an Internet access router uses DHCP client and server functions, as well as NAT. 1828xbook.fm Page 511 Thursday, July 26, 2007 3:10 PM 16 CHAPTER WAN Concepts Chapter 4, “Fundamentals of WANs,” introduced two important WAN technologies common in enterprise networks today: Leased lines, which use either High-Level Data Link Control (HDLC) or Point-to- ■ Point Protocol (PPP) Frame Relay ■ Part IV of this book covers the remainder of the WAN-specific topics in this book. In particular, this chapter examines a broader range of WAN technologies, including commonly used Internet access technologies. Chapter 17, “WAN Configuration,” focuses on how to implement several features related to WAN connections, including several Layer 3 services required for a typical Internet connection from a small office or home (SOHO) today. “Do I Know This Already?” Quiz The “Do I Know This Already?” quiz allows you to assess if you should read the entire chapter. If you miss no more than one of these eight self-assessment questions, you might want to move ahead to the “Exam Preparation Tasks” section. Table 16-1 lists the major headings in this chapter and the “Do I Know This Already?” quiz questions covering the material in those headings so you can assess your knowledge of these specific areas. The answers to the “Do I Know This Already?” quiz appear in Appendix A. “Do I Know This Already?” Foundation Topics Section-to-Question Mapping Table 16-1 Foundation Topics Section Questions WAN Technologies 1–5 IP Services for Internet Access 6–8 1828xbook.fm Page 512 Thursday, July 26, 2007 3:10 PM 512 Chapter 16: WAN Concepts Which of the following best describes the function of demodulation by a modem? 1. Encoding an incoming analog signal from the PC as a digital signal for transmis- a. sion into the PSTN Decoding an incoming digital signal from the PSTN into an analog signal b. Encoding a set of binary digits as an analog electrical signal c. Decoding an incoming analog electrical signal from the PSTN into a digital d. signal Encoding a set of binary digits as a digital electrical signal e. Which of the following standards has a limit of 18,000 feet for the length of the 2. local loop? ADSL a. Analog modems b. ISDN c. Cable Internet service d. Which of the following is true regarding the location and purpose of a DSLAM? 3. Typically used at a home or small office to connect the phone line to a DSL router a. Typically used at a home or small office instead of a DSL router b. Typically used inside the telco’s CO to prevent any voice traffic from reaching the c. ISP’s router Typically used inside the telco’s CO to separate the voice traffic from the data d. traffic Which of the following remote-access technologies support specifications that allow 4. both symmetric speeds and asymmetric speeds? ...