Two BGP peers connected through a routed firewall are unable to establish a peering relationship. What could be the most likely cause?
A.
BGP peers must be Layer 2-adjacent.
B.
EBGP multihop is not configured.
C.
The firewall is not configured to allow IP protocol 89.
D.
The firewall is not configured to allow UDP 179.
Explanation:
It seems the key piece of information in the question is routed firewall. Since the firewall is in routed mode and not in transparent mode and the fact that BGP packets are sent with a TTL of 1 by default, BGP multihop is needed to increase the TTL of the packets so they can successfully traverse the firewall.Still not a fan of this kind of ‘interpretive’ question from Cisco