Which statement about PAT (NAT overload) is true?

• A. NAT translates private addresses to public addresses along with port translation.
• B. PAT uses a pool of many public IPs to map each internal host.
• C. PAT uses a single public IP with port numbers to multiplex many internal hosts.
• D. PAT eliminates the need for NAT entirely.

Answer: (C)

The main idea is that PAT (NAT overload) lets many inside devices share a single public IP by using port numbers to tell them apart. When an internal host talks outward, the router rewrites the source to the single public IP and assigns a unique source port for that connection. It keeps a translation entry linking that public port (and protocol) to the internal host’s private IP and port. Because each flow uses a different port, many internal hosts can be active at once behind the same public address, and return traffic is routed back correctly by matching the port to the right internal host.

This is why the statement describing PAT as using one public IP with port numbers to multiplex many internal hosts is the best fit. Using a pool of many public IPs would contradict PAT’s single-IP multiplexing, and PAT does not eliminate NAT entirely. While NAT with port translation is related, the defining feature of PAT is the single public IP that is multiplexed by port numbers.