Which of the following is an example of an Interior Gateway Protocol used for routing inside an autonomous system?

• A. BGP Border Gateway Protocol
• B. NAT Network Address Translation
• C. PAT Port Address Translation
• D. RIP

Answer: (D)

Interior Gateway Protocols are designed to run inside a single autonomous system, sharing routing information to determine paths within that network boundary. RIP fits this role because it is designed to manage routing inside an AS using hop count as its metric and updates the routing table with routes learned from neighbors within the same AS. BGP, on the other hand, is an Exterior Gateway Protocol used to exchange routes between different autonomous systems, so it doesn’t satisfy the requirement of routing inside one AS. NAT and PAT are address translation mechanisms, not routing protocols; they don’t participate in exchanging dynamic route information. Therefore, RIP is the interior gateway protocol example.