PAT (Port Address Translation)

• A. Port Address Translation. A form of NAT that translates private IP addresses to public IP addresses, and private IP addresses back to public IP addresses. PAT uses a single public IP address. Compare to DNAT.
• B. DNAT
• C. Private Address Translation
• D. Protocol Address Translation

Answer: (A)

Port Address Translation lets many private hosts share a single public IP by multiplexing connections through port numbers. When an internal device sends traffic, the NAT rewrites the source address to the public IP and assigns a unique source port, creating a mapping from that public port to the private IP and port. Replies come back to the public IP and port, and the NAT uses the table to reverse the translation and deliver the data to the correct internal host. This description matches PAT’s purpose and behavior: a NAT variant that uses one public IP while distinguishing multiple internal connections by port. The other terms refer to different concepts—Destination NAT, which changes where traffic goes into the network, and nonstandard or incorrect terms—so they don’t describe PAT.