Which statement best describes periodic updates in BGP?

• A. Periodic updates are required to maintain routes and propagate changes.
• B. No periodic updates are required; the connection is reliable and only changes are sent.
• C. Updates are sent only when the session is established.
• D. BGP uses UDP for its updates.

Answer: (B)

Updates in BGP are driven by changes in routing information and are carried inside a TCP session, not on a fixed schedule. Once a neighbor session is established, BGP advertisements are sent only when routes change, and withdrawals are sent when routes disappear. The TCP connection provides reliability, so there’s no need for periodic, timer-based refreshes of the whole table—the protocol simply propagates incremental changes as they occur. Keepalive messages exist to verify the session is alive, but they are not routing updates.

This is why the statement describing no periodic updates and only changes being sent best captures how BGP operates. In contrast, the idea of periodic updates implies a timer-driven refresh, which BGP does not perform; updates are not limited to the establishment phase and can continue whenever changes happen; and BGP does not use UDP for its updates, it uses TCP.