cisco ccna 4 exam answers

cisco ccna 4 exam answers.The previous example of port address redirection shows that PAT is performed dynamically by the address translation device, but this will not work in some cases. For example, an ISP may only assign you a public IP address, and in order for internal users to be able to access external resources, you need to use PAT. if you want external users to be able to access internal services, such as web servers, using dynamic PAT will not work. For this problem, another solution can be used: static PAT - often referred to as Port Address Redirection (PAR). o The following is a simple example to illustrate how PAR works. Suppose your ISP has assigned you only one IP address: 199.199.199.1, and you need to give internal users access to the external network while giving external users access to the internal web server. To use a static PAT, you configure the address translation device to see not only the target IP address (199.199.199.1), but also the target port number (80 for the Web server). o You create a static PAT entry so that when the address translation device sees this combination of address and port number, it converts it to use the internal local IP address (and possibly the port number) for the internal server. port numbers). For example, suppose that the given network is shown in Figure 22.1. In this example, the ISP has assigned you only one IP address - 200.200.200.1, which must be configured on the router's interface S0±o This presents a problem because you have an internal Web server and want to make it accessible to external users. Port address redirection can be used to solve this problem: Configure a static PAT entry on the router that redirects traffic sent to 200.200.200.1 and port 80 to 10.L1.1 and port 80. if PAR is not configured, the router will try to handle the Web connection itself because the address 200.200.200.1 is assigned to one of its interfaces.Exam Essentials Port Address Redirection allows you to redirect application traffic sent to one address to another.Chapter 22 Address Translation 59122.2.4 Advantages of Address TranslationAs stated at the beginning of this chapter, address translation is commonly used to provide a virtually unlimited number of addresses as well as to hide network addressing schemes. Another advantage of address translation is that when you change ISPs or merge with another company, you can keep the existing addressing scheme and make the necessary changes to the address translation device, which makes address management easier.Address translation also has the significant advantage of allowing you to more tightly control traffic to and from your network. For example, if a private address is used internally, all traffic going in and out must pass through the address translation device, which makes security and business policies much easier to implement.Exam Essentials The benefits of address translation include saving public addresses, limiting access to resources by external devices (which improves security), and eliminating the need to re-address devices after changing ISPs.22.2.5 Disadvantages of Address TranslationWhile address translation solves many problems and has many advantages, it also has disadvantages. The following are three major problems with address translation.. Adding latency to all connections .