What is the main goal of BGP?

• A. To provide an interdomain routing system with a loop-free exchange of routing information between autonomous systems.
• B. To minimize hop count within a single AS.
• C. To route only within a single ISP’s network.
• D. To replace all IGPs with a single protocol.

Answer: (A)

BGP is designed to enable routing between different networks on the Internet in a scalable way, by exchanging reachability information across autonomous systems in a loop-free manner. It uses a path-vector approach (AS_PATH) so each network can see which other ASes a route traverses, and operators can apply policies to decide which paths to prefer. This loop-free exchange is what keeps routes from looping as information crosses many networks.

Inside a single autonomous system, routing typically relies on interior protocols that optimize paths locally and minimize hops, which is the job of IGPs rather than BGP. BGP’s role isn’t to minimize hops within one AS, but to connect multiple networks together reliably and with policy control.

BGP is also not limited to routing only within one ISP’s network; it is specifically meant for interdomain routing between many networks, including ISPs, enterprises, and other organizations. It isn’t intended to replace all IGPs with a single protocol; inside each AS, IGPs (or similar interior routing methods) continue to operate alongside BGP to handle internal routing.

So the best description is that BGP’s main goal is to provide an interdomain routing system that allows loop-free exchange of routing information between autonomous systems.