Static NAT Overload Configuration | Cisco CCNA Exam 200-125

Effect of the overload keyword in static NAT configuration

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What is the effect of the overload keyword in a static NAT translation configuration?



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A. B. C. D.


The "overload" keyword in a static NAT (Network Address Translation) configuration is used to allow multiple internal devices to share a single public IP address. When the "overload" keyword is used, it enables Port Address Translation (PAT) or NAT overload, which means that the router uses a unique source port number to map the internal IP addresses to the public IP address.

Here's how it works:

  • When a device from the inside network sends traffic to the outside network, the router replaces the source IP address of the packet with the public IP address and assigns a unique port number to the packet.
  • When the router receives a response from the outside network, it looks at the destination port number in the packet and uses it to determine which internal device the response should be forwarded to. It then replaces the destination IP address and port number with the corresponding internal IP address and port number.

The benefit of using NAT overload is that it allows multiple devices on the inside network to access the internet using a single public IP address. Without NAT overload, each device would require its own public IP address, which is not feasible due to the limited availability of public IP addresses.

Therefore, the correct answer to the question is A. It enables port address translation. Option B is incorrect because the "overload" keyword does not enable the use of a secondary pool of IP addresses. Option C and D are also incorrect because the "overload" keyword does not affect the inside or outside interfaces.