Cisco CCNA Exam | Danger of "permit any" Entry in NAT Access List

The Danger of the "Permit Any" Entry in a NAT Access List

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What is the danger of the permit any entry in a NAT access list?



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A. B. C. D.


The correct answer is D.

NAT (Network Address Translation) is a process that translates private IP addresses to public IP addresses for communication over the internet. NAT access lists are used to define which IP addresses or IP ranges are allowed to access the NAT process.

The "permit any" entry in a NAT access list allows any IP address to be translated by the NAT process. While this may seem convenient, it can also be dangerous, as it can prevent the correct translation of IP addresses on the inside network.

For example, suppose a company has a private IP address range of on its internal network and uses NAT to translate those addresses to a public IP address for internet communication. If a "permit any" entry is added to the NAT access list, any IP address, including those that are not part of the range, can be translated. This can lead to unintended consequences, such as a user on the internal network being assigned a public IP address that conflicts with another device on the internet.

Furthermore, allowing any IP address to be translated can also open up security vulnerabilities. For example, an attacker could use a spoofed IP address to gain access to the internal network, bypassing security measures such as firewalls.

In contrast, if specific IP addresses or IP ranges are specified in the NAT access list, only those addresses will be translated, providing greater control and security.

Options A, B, and C are incorrect because they do not accurately describe the danger of the "permit any" entry in a NAT access list. Overloaded resources on the router and assigning too many addresses to the same interface are potential consequences of NAT, but they are not specific to the "permit any" entry in the access list. Disabling the overload command would not be affected by the "permit any" entry.