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Networking Fundamentals · Foundational

Port Address Translation (PAT)

NAT that maps many inside addresses to one (or a few) public addresses by tracking unique source port numbers; also called NAT overload.

Definition

PAT records each connection's inside address and port and assigns a unique outside port, allowing thousands of simultaneous sessions to share one public IP. It is what home routers and most enterprise Internet edges perform. Inbound connections cannot be initiated unless a port forward or static mapping exists.

Example

ip nat inside source list 1 interface g0/1 overload enables PAT on a Cisco router.

Exam tip

"Overload" on Cisco equals PAT; it is the answer for "many private hosts, one public IP."

Don't confuse it with

Related terms