H12-821_V1.0 · Question #598
Which of the following information does the BGP Open message carry? (Multiple choice)
The correct answer is A. BGP Router ID B. Hold Time C. Local Autonomous System (AS) Number. BGP Open messages are exchanged first when two BGP peers establish a session, and they carry the parameters needed to negotiate the connection itself: the BGP Router ID (A), Hold Time (B), and Local AS Number (C). These three fields allow each peer to identify who it's talking…
Question
Options
- ABGP Router ID
- BHold Time
- CLocal Autonomous System (AS) Number
- DRouting attributes
How the community answered
(53 responses)- A74% (39)
- D26% (14)
Explanation
BGP Open messages are exchanged first when two BGP peers establish a session, and they carry the parameters needed to negotiate the connection itself: the BGP Router ID (A), Hold Time (B), and Local AS Number (C). These three fields allow each peer to identify who it's talking to, agree on session keepalive timing, and determine whether the relationship is iBGP or eBGP.
Why D is wrong: Routing attributes (such as AS_PATH, NEXT_HOP, MED, LOCAL_PREF) are carried in Update messages, not Open messages. Update messages are sent after the session is established to advertise or withdraw routes.
Memory tip: Think of the Open message as a "handshake ID card" - you show your name (Router ID), your country (AS Number), and agree on how long to wait before assuming the other person left (Hold Time). You don't discuss actual routes until you're properly introduced - that happens in Update messages.
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