Recognizing NAT methods on Cisco IOS: Which listed items correspond to standard NAT methods supported on Cisco routers?

Introduction / Context:
Cisco IOS supports several common NAT methods used for IPv4 address conservation and policy enforcement. Distinguishing the canonical methods helps you read and write configurations accurately and avoid misinterpreting terminology.

Given Data / Assumptions:

• Items listed: 1) Static, 2) IP NAT pool, 3) Dynamic NAT, 4) double-translation, 5) Overload.
• We must select the set that represents recognized NAT methods.
• IOS classic NAT focus (not ASA twice NAT features).

Concept / Approach:

Classic IOS NAT methods are: Static NAT (one-to-one fixed mapping), Dynamic NAT (pool-based mapping allocated on demand), and NAT Overload (PAT, many-to-one with port multiplexing). “IP NAT pool” is a configuration element, not a separate method, and “double-translation” is not used as a formal IOS NAT method name in classic contexts.

Step-by-Step Solution:

Verification / Alternative check:

IOS configuration guides show syntax: ip nat inside source static, ip nat inside source list … pool …, and overload keyword for PAT. Pools support dynamic or policy NAT but are not a method by themselves.

Why Other Options Are Wrong:

Including “IP NAT pool” elevates a building block to a “method.”

“Double-translation” is not a standard IOS term for a core method in this context.

Common Pitfalls:

Confusing PAT (overload) with dynamic NAT; treating address pools as a separate method rather than a resource used by dynamic or policy NAT.

Final Answer:

1, 3 and 5