Cisco Certified Network Associate (CCNA) Practice Exam

What command is used to configure NAT with PAT in Cisco routers?

1. ip nat pool

2. ip nat inside source list

3. access-list permit

4. copy run start

The correct answer is: ip nat pool

The correct command for configuring NAT with PAT (Port Address Translation) in Cisco routers is "ip nat inside source list." This command allows you to associate an access control list (ACL) with the NAT configuration, enabling the router to translate the private IP addresses of devices within your network to a single public IP address. This process involves using different port numbers to keep track of multiple translations using the same public IP, which is the essence of PAT. While the "ip nat pool" command is utilized to define a range of public IP addresses that can be used for NAT, it does not specifically implement PAT. Instead, it is often used in conjunction with static NAT configurations or other forms of dynamic NAT, where multiple devices are translated to multiple addresses rather than through a single public IP with port differentiation. The other options, like "access-list permit," relate to defining rules for what traffic may be translated, but they don’t configure NAT directly. The command "copy run start" is unrelated to NAT and is used for saving the current configuration to the startup configuration file. Therefore, the best choice for configuring NAT with PAT is indeed "ip nat inside source list."