Common things to look for when troubleshooting different protocols

jambla85

Hello. I'm just trying to memorizedifferent things to look for to trouble shoot common problems so that when Ihit the Sims in the test I can hopefully find the problem quickly. Here’s whatI am thinking below, please add to the list for any problems that may crop upin the CCNA exam.

OSPF
Area mismatch
Wrong network advertised
Advertised interface down
Passive Interface
Hello and dead timers misconfigured
Make sure neighbors are in the same subnet
Make sure two routers do not have the same OSPF ID

EIGRP
Autonomous mismatch
Wrong networks advertised
Advertised interface down
PassiveInterfaces
Makesure neighbors are in the same subnet (verify neighbors quickly with thecommand show ip eigrp interfaces)
Checkthat two routers do not have the same EIGRP ID
Makesure no auto summary is on when using VLSM
VTP
Check the versions match
Make sure the domain name matches
Make sure the passwords match
Make sure the mode is set correctly



WAN
Check the encapsulation matches
Check neighbors are in the same subnet
Check username and password match
Check authentication matches
Check for no keep alive

ACL
Make sure the list is applied the right interface and direction
Make sure the wildcard mask is specifying the correct range


I'm sure there is lots more but that's what has come from the top of my head!

jvrlopez

Auto summery on EIGRP.

Zartanasaurus

OSPF
Matching interface types
Matching interface MTU

OSPF/EIGRP
Matching authentication configuration

VTP
Trunk interfaces between switches

ACL
Order of operations
Port/protocol matches what you are trying to permit/deny
Source port vs destination port matches