Which statement best describes how BGP neighbors are maintained?

• A. By a UDP session with periodic keepalives.
• B. By broadcasting hello packets to all peers.
• C. By a TCP session; keeps track of state with keepalive messages.
• D. By a stateless, connectionless exchange.

Answer: (C)

BGP neighbors are maintained over a TCP connection between the two routers. The TCP session provides reliable, in-order delivery, and BGP sits on top of that connection to manage the neighbor state. Once the TCP session is established, BGP exchanges OPEN messages to negotiate parameters, then uses periodic KEEPALIVE messages to show the neighbor is still reachable and to keep the session active. If no BGP messages are received within the negotiated Hold Time, the session is considered failed and is closed. This combination—a TCP-backed session with BGP’s own keepalive mechanism to monitor liveness—best describes how neighbors are maintained.