A network administrator is troubleshooting a BGP network where some BGP routes are missing from BGP tables. The administrator has verified that BGP peers were formed as expected. What are two possible reasons that routes would not appear in the BGP table or the routing table? (Choose two.)

IT Questions Bank › Category: CCNP › A network administrator is troubleshooting a BGP network where some BGP routes are missing from BGP tables. The administrator has verified that BGP peers were formed as expected. What are two possible reasons that routes would not appear in the BGP table or the routing table? (Choose two.)

Question:

the default route being used to reach a neighbor
route filtering configuration
misconfigured timers
better source of information available
TCP port 179 being blocked by an ACL or a firewall

Explanation: BGP peers are the foundation of BGP information sharing. Without peers, BGP will not learn BGP routes. Some common reasons that BGP routes might be missing from either the BGP table or the routing table include the following:

Missing or bad network mask command : An accurate network command is needed to advertise routes.
Next-hop router not reachable : To use a BGP route, the next hop must be reachable.
BGP split-horizon rule : A router that learns BGP routes through an IBGP peering does not share those routes with another IBGP peer.
Better source of information : If the same network is learned from a more reliable source, it is used instead of the BGP-learned information.
Route filtering : A filter might be preventing a route from being shared with neighbors or learned from neighbors.

Exam with this question: CCNP Enterprise: Advanced Routing (Version 8.0) – BGP Exam

BGP split-horizon rule
mismatched authentication being used
missing or bad network mask command
no Layer 3 connectivity to neighbor routers
only EBGP being used to establish adjacency

Missing or bad network mask command: An accurate network command is needed to advertise routes.
Next-hop router not reachable: To use a BGP route, the next hop must be reachable.
BGP split-horizon rule: A router that learns BGP routes through an IBGP peering does not share those routes with another IBGP peer.
Better source of information: If the same network is learned from a more reliable source, it is used instead of the BGP-learned information.
Route filtering: A filter might be preventing a route from being shared with neighbors or learned from neighbors.

Exam with this question: Chapter 14: Quiz - Troubleshooting BGP CCNPv8 ENARSI