Also called NAT overload, which translation technique lets many private IP addresses share a single public IP by using different port numbers?

Also called NAT overload, which translation technique lets many private IP addresses share a single public IP by using different port numbers?

• A. NAT Network Address Translation
• B. PAT Port Address Translation
• C. Static NAT
• D. Dynamic NAT

Answer: (B)

Port Address Translation (PAT), also called NAT overload, lets many private IP addresses share a single public IP by using different port numbers. When an internal host communicates outward, the edge router replaces the source private IP with the public IP and assigns a unique source port for that session. The router keeps a translation table that maps the public IP and port back to the specific private IP and port. Replies coming back to the public IP and port are then forwarded to the correct internal host using that table entry. This multiplexing of multiple internal sessions over one public address is what enables many devices to access external networks simultaneously. This differs from other NAT types: static NAT maps one private IP to one public IP (no sharing), and dynamic NAT uses a pool of public addresses but still pairs each internal host with a public address rather than multiplexing many hosts over a single public IP via port numbers.

Port Address Translation (PAT), also called NAT overload, lets many private IP addresses share a single public IP by using different port numbers. When an internal host communicates outward, the edge router replaces the source private IP with the public IP and assigns a unique source port for that session. The router keeps a translation table that maps the public IP and port back to the specific private IP and port. Replies coming back to the public IP and port are then forwarded to the correct internal host using that table entry. This multiplexing of multiple internal sessions over one public address is what enables many devices to access external networks simultaneously.

This differs from other NAT types: static NAT maps one private IP to one public IP (no sharing), and dynamic NAT uses a pool of public addresses but still pairs each internal host with a public address rather than multiplexing many hosts over a single public IP via port numbers.