Which translation uses a single public IP with different source ports to support multiple internal sessions?

Which translation uses a single public IP with different source ports to support multiple internal sessions?

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

Answer: (A)

This question tests how a single public IP can support many internal sessions by using different source ports. Port Address Translation (PAT) overloads one public address by assigning a unique source port for each internal connection. When an inside device starts a session, the router rewrites the source IP to the public IP and selects a distinct port, keeping a translation table that maps the inside address and port to the public address and port. This lets multiple concurrent conversations appear to come from the same public IP because the port number differentiates each session. In contrast, one-to-one mappings or dynamic pools use separate public IPs or don’t rely on port multiplexing in the same way, so they don’t achieve the single-IP-with-multiple-ports behavior described.

This question tests how a single public IP can support many internal sessions by using different source ports. Port Address Translation (PAT) overloads one public address by assigning a unique source port for each internal connection. When an inside device starts a session, the router rewrites the source IP to the public IP and selects a distinct port, keeping a translation table that maps the inside address and port to the public address and port. This lets multiple concurrent conversations appear to come from the same public IP because the port number differentiates each session. In contrast, one-to-one mappings or dynamic pools use separate public IPs or don’t rely on port multiplexing in the same way, so they don’t achieve the single-IP-with-multiple-ports behavior described.