CCNP Practice Question: Which type of NAT translates multiple inside…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Static NAT

  Why it's wrong here

  Static NAT creates a permanent, one-to-one mapping between a private inside address and a public outside address. It does not involve any port multiplexing, so a single public IP can only represent one internal host at a time. This makes it suitable for inbound services (e.g., a web server) but wasteful and impractical for large numbers of internal users sharing a single public IPv4 address.

• ✗

  Dynamic NAT

  Why it's wrong here

  Dynamic NAT maps multiple inside addresses to a pool of public addresses on a first-come, first-served basis, but each translation still consumes one entire public IP per active session. When the pool is exhausted, no additional translations occur, and like static NAT, it lacks port-level multiplexing. It is useful for outbound-only environments with enough public addresses, but it does not achieve the address conservation that PAT provides.

• ✓

  Port Address Translation (PAT)

  Why this is correct

  Port Address Translation (PAT), also known as NAT overload, is correct because it multiplexes thousands of inside hosts to a single outside IPv4 address by leveraging the transport-layer port number (TCP or UDP) to identify each unique session. The router maintains a translation table that maps (inside local address, inside local port) to (outside global address, outside global port), allowing many internal devices to share one public address simultaneously. This directly addresses the IPv4 exhaustion problem and is the standard method used in home routers and enterprise edge devices.

• ✗

  Policy NAT

  Why it's wrong here

  Policy NAT is used to perform NAT based on extended access-control-list matching criteria (source, destination, protocol, and port), but it does not inherently perform port multiplexing. It can be used to enforce different translation rules for different traffic types, such as translating some traffic to one public IP and other traffic to a different public IP or to a PAT pool. The concept is about policy-driven selection of translation behavior, not about conserving addresses through port-level multiplexing, so it is not the mechanism that allows multiple inside addresses to share a single outside IP.