NAT Overload — One Public IP for Many Internal Users Which flavor of Network Address Translation enables many inside hosts to share a single public IPv4 address when accessing the Internet by multiplexing with transport ports?

Introduction / Context:
IPv4 scarcity led to widespread use of address translation at network edges. When many users must share one public address, Port Address Translation (PAT) is typically used to distinguish sessions by port numbers while rewriting source addresses.

Given Data / Assumptions:

• Multiple inside clients access external services simultaneously.
• The edge device has only one public IPv4 address available.
• Standard consumer and enterprise NAT behavior is assumed.

Concept / Approach:
PAT, often called NAT overload, maps many inside local addresses to a single inside global address by translating source transport ports (TCP/UDP) uniquely per flow. Static NAT maps one-to-one between a private and a public address; Dynamic NAT maps from a pool on a one-to-one basis per session but still consumes one public per inside host at a time. Only PAT allows many-to-one at the same time without exhausting the public address pool.

Step-by-Step Solution:
Identify the requirement: many hosts, single public IP.Eliminate static and dynamic one-to-one mappings.Choose PAT (overload) to multiplex flows by ports.Confirm with typical configuration: ip nat inside source list ACL interface overload.

Verification / Alternative check:
Observe NAT translation tables: many inside sources map to one global address with distinct port tuples under PAT.

Why Other Options Are Wrong:

• Static/Dynamic: Consume a public IP per inside host, not suitable for many-to-one sharing.
• NAT (generic): Too broad; does not specify the many-to-one port multiplexing.
• Double NAT: Refers to two separate NAT domains, not to many-to-one operation.

Common Pitfalls:
Confusing “dynamic NAT” with PAT; only PAT provides many-to-one simultaneous connections using port translation.

Final Answer:
PAT