What is the primary function of BGP?

• A. Exchange routing information between autonomous systems
• B. End-user authentication
• C. DNS resolution for routes
• D. Encrypt traffic between routers

Answer: (A)

BGP is used to exchange routing information between autonomous systems, allowing networks to share which IP prefixes they can reach and to apply policies that determine which paths are preferred. It operates by advertising reachability and carrying path attributes (like AS_PATH and NEXT_HOP) that enable operators to control routing decisions and prevent loops, enabling scalable interdomain routing across the Internet.

End-user authentication, DNS resolution for routes, and encryption of traffic between routers aren’t the primary roles of BGP. Authentication can be configured, but that’s not its core function; DNS handles domain name resolution, not routing reachability; and encryption of traffic is not what BGP provides by default.