Upon the successful establishment of a TCP session between peers, what type of BGP message is exchanged?

Question

Options

• AOpenSent
• BKeepalive
• COpen
• DNotification
• EUpdate

• B
  4% (1)
• C
  88% (23)
• E
  8% (2)

Explanation

When a TCP session is successfully established between BGP peers, an Open message is the first BGP message exchanged - it initiates the BGP session by advertising the sender's AS number, BGP version, Hold Time, and Router ID, allowing peers to negotiate session parameters.

Why the distractors are wrong:

• A. OpenSent - This is a BGP state (not a message type) in the finite state machine, representing that an Open message has been sent and the router is awaiting a reply.
• B. Keepalive - Keepalives are sent after a successful Open exchange to maintain the session; they confirm acceptance of the Open but aren't the first message sent.
• D. Notification - Sent only when an error occurs, typically to tear down the session.
• E. Update - Sent after the session is fully established to advertise or withdraw routing prefixes.

Memory tip: Think of BGP like a phone call - you first say "Hello, this is AS 65001" (Open), then stay on the line with periodic "you still there?" checks (Keepalive), and eventually share routing news (Update). The Open message is always the handshake greeting.

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