CompTIA A+ 220-701/702 Practice Exam

Answer - A - BGP sends the notification message to its neighbors when an error condition is detected.

Key Takeaway: Notification messages are used to signal when something is wrong with the BGP session. A notification will be sent when any of the following occurs: an unsupported option is sent in an OPEN message or a peer fails to send an update or keep-alive message. When an error is detected, the BGP session is closed. The open message opens a BGP communication session between peers and is the first message sent by each side after a transport-protocol connection is established. An update message is used to provide routing updates to other BGP systems, allowing routers to construct a consistent view of the network topology. The keep-alive message notifies BGP peers that a device is active.