Two of the core routers are not able to establish routing protocol adjacency with each other. To best effectively troubleshoot this issue, which four things should be verify? (Choose four)
A.
The routers interface link that provides connectivity between the two routers is in the UP state.
B.
The routing protocol configurations an each router match (such as routing protocol timers and routing protocol authentication).
C.
NTP is configured an both routers and the clocks are synchronized between the two routers
D.
The two routers can ping each other.
E.
If a firewall exists in the path between the two routers, it is properly configured.
F.
The MPLS (LDP) adjacency is up between the two routers.