Using new backup router in spite of faulty one in ospf domain but relationship with neighbor in one interface only not working , what is the reason of this problem? (Choose Two)
A. area Id match
B. authentication mismatch
C. process id of ospf not match
D. ospf timers not match
E. MTU mismatch
_ONE INTERFACE ONLY_
timers would cause all adjacencies to fail!
for me, correct is MTU and Authentication, the only available parameters you can modify in interface configuration mode.
B E
Sorry, you CAN change timers per-interface ! B, D, E
MTU may depends on the size of DBDs, so i would go for B, D
also an interface can be assigned to an area so A could be a potential correct answer
BD is Correct
https://learningnetwork.cisco.com/thread/37638
OSPF MTU Mismatch
“The Neighborship will be formed” but it not form “FULL” Adjecency. i.e., DBD exchange might not happen and the neighborship will be stuck in “EXSTART / EXCHANGE” state.
https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13684-12.html
Neighbors Stuck in Exstart/Exchange State
The problem occurs most frequently when attempting to run OSPF between a Cisco router and another vendor’s router. The problem occurs when the maximum transmission unit (MTU) settings for neighboring router interfaces don’t match. If the router with the higher MTU sends a packet larger that the MTU set on the neighboring router, the neighboring router ignores the packet.0 When this problem occurs, the output of the show ip ospf neighbor command displays output similar that shown below.
B, D, E.
Every answer is interface-level config and every mismatch will prevent establish relationship.
BD
https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/12151-trouble-main.html#anc24
Troubleshoot OSPF Init State
Troubleshoot the Hello/Dead Interval Mismatch
https://learningnetwork.cisco.com/thread/37638