CCENT/CCNA ICND1 Official Exam Certification Guide - Chapter 12

IP Addressing and Subnetting Các khái niệm và ứng dụng của địa chỉ IP và subnetting cũng có thể là nhiều nhất chủ đề quan trọng để hiểu cả hai là một kỹ sư mạng chuẩn bị tốt và cho sẵn sàng để làm tốt trên các ICND1, ICND2, và các kỳ thi CCNA. Để thiết kế một mạng mới, các kỹ sư phải có khả năng để bắt đầu với một số phạm vi địa chỉ IP và phá vỡ nó thành các phân khu được gọi là mạng con, lựa chọn đúng kích cỡ của mỗi mạng con để đáp ứng yêu...
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CCENT/CCNA ICND1 Official Exam Certification Guide - Chapter 12 1828xbook.fm Page 329 Thursday, July 26, 2007 3:10 PM Part III: IP Routing Chapter 12 IP Addressing and Subnetting Chapter 13 Operating Cisco Routers Chapter 14 Routing Protocol Concepts and Configuration Chapter 15 Troubleshooting IP Routing 1828xbook.fm Page 330 Thursday, July 26, 2007 3:10 PM This chapter covers the following subjects: Exam Preparation Tools for Subnetting: This section lists the various tools that can help you practice your subnetting skills. IP Addressing and Routing: This section moves beyond the basic concepts in Chapter 5, “Fundamentals of IP Addressing and Routing,” introducing the purpose and meaning of the subnet mask. Math Operations Used When Subnetting: This section explains how to convert between IP address and subnet mask formats. Analyzing and Choosing Subnet Masks: This section explains the meaning behind subnet masks, how to choose a subnet mask to meet stated design goals, and how to interpret a mask chosen by someone else. Analyzing Existing Subnets: This section shows how to determine an IP address’s resident subnet, broadcast address, and range of addresses in the subnet. Design: Choosing the Subnets of a Classful Network: This section explains how to find all subnets of a single classful network. 1828xbook.fm Page 331 Thursday, July 26, 2007 3:10 PM 12 CHAPTER IP Addressing and Subnetting The concepts and application of IP addressing and subnetting may well be the most important topics to understand both for being a well-prepared network engineer and for being ready to do well on the ICND1, ICND2, and CCNA exams. To design a new network, engineers must be able to begin with some IP address range and break it into subdivisions called subnets, choosing the right size of each subnet to meet design requirements. Engineers need to understand subnet masks, and how to pick the right masks to implement the designs that were earlier drawn on paper. Even more often, engineers need to understand, operate, and troubleshoot pre-existing networks, tasks that require mastery of addressing and subnetting concepts and the ability to apply those concepts from a different perspective than when designing the network. This chapter begins Part III of the book, which is focused on the role of routers in an internetwork. As introduced in Chapter 5, the network layer defines and uses addressing, routing, and routing protocols to achieve its main goals. After this chapter goes into depth on addressing, the rest of the chapters in Part III focus on how to implement IP addresses, routing, and routing protocols inside Cisco routers. All the topics in this chapter have a common goal, which is to help you understand IP addressing and subnetting. To prepare you for both real jobs and the exams, this chapter goes far beyond the concepts as covered on the exam, preparing you to apply these concepts when designing a network and when you operate and troubleshoot a network. Additionally, this chapter creates a structure from which you can repeatedly practice the math processes used to get the answers to subnetting questions. “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 14 self-assessment questions, you might want to move ahead to the “Exam Preparation Tasks” section. Table 12-1 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 t ...