3 Planning Internet

Connectivity

Exam Objectives in this Chapter:

■

Plan an Internet connectivity strategy.

■

Troubleshoot connectivity to the Internet.

❑

Diagnose and resolve issues related to Network Address Translation (NAT).

❑

Diagnose and resolve issues related to name resolution cache information.

❑

Diagnose and resolve issues related to client configuration.

Why This Chapter Matters

In this chapter, you learn about developing an Internet access strategy that

enables your network users to access the services they need efficiently and

securely. To connect a network to the Internet, you must select an appropriate

connection type based on the network’s requirements, determine what IP

addresses you will use on your client computers, and decide how you will protect

the network from Internet intruders.

Although it is easy to connect a network to the Internet, doing so with appropriate

security complicates the process considerably. This chapter examines the various

types of shared Internet connections you can use for a network, describes how to

evaluate a network’s Internet access needs, and describes the methods you can use to

protect the network from Internet predators. When planning an Internet access solu-

tion for your network, you might think that the security hazards in your situation are

minimal and that the potential for abuse of the Internet connection by your own users

is not an issue. Many network administrators feel this way at first and subsequently

change their minds, usually when something bad happens. It is a good idea to con-

sider these factors at the start so that you can implement an Internet access solution

that is sufficient and secure, before you lose any money or data.

Lessons in this Chapter:

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Lesson 1: Planning an Internet Connectivity Infrastructure . . . . . . . . . . . . . . 3-3

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Lesson 2: Selecting Routers and ISPs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15

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Lesson 3: Securing and Regulating Internet Access . . . . . . . . . . . . . . . . . . . 3-24

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Lesson 4: Troubleshooting Internet Connectivity . . . . . . . . . . . . . . . . . . . . 3-34

3-1