Goldfish Networks wordmark
IntermediatePublished 2026-08-26

CCNA Break/Fix: The OSPF Neighbour That Never Forms

Archive lab

Daily CCNA troubleshooting repair lab. Two routers share a /30 transit link and both run OSPF process 1 with explicit router-ids. IP connectivity over the transit is fine, but the OSPF adjacency never forms and remote routes are missing. Your job: work the neighbour state without changing working addressing or adding static routes. Bring the OSPF peering to FULL so the branch LAN appears on the core router.

Track
Est. time
55 minutes
Difficulty
Intermediate
Topics

Learning objectives

  • Diagnose an OSPF neighbour that never forms when IP connectivity is otherwise healthy
  • Correlate symptoms across show ip ospf neighbor, show ip ospf interface brief, and show run | section router ospf
  • Apply the correct OSPF network statement and wildcard to activate OSPF on a specific transit subnet
  • Validate OSPF route installation and end-to-end reachability from hosts

Troubleshooting focus

  • Transit pings succeed between routers, but show ip ospf neighbor is empty on both sides
  • No OSPF-learned routes to the branch LAN on the core router
  • OSPF process exists with router-id set, yet no interface on the transit shows as OSPF-enabled

Topology

Subscribe to preview this lab's topology.

See plans

Related labs

More hands-on Cisco Modeling Labs practice on the same track and topics.

Grade your work

How this lab is graded
  • Build it your way. Where a lab lets you choose a value — a VLAN name, an interface description — grading checks that you configured it, not which name you picked. Names that another line has to reference, like an ACL applied with access-class, are stated in the guide and do have to match.
  • Addresses, modes and protocol keywords are exact. An IP address, a subnet mask, switchport mode trunk, an encapsulation — these carry the meaning of the lab, so they are graded as written in the guide.
  • Grading reads your saved configuration. Export the lab from CML after you have configured it, and make sure anything you set is in the running-config — a change that only exists in a terminal session never reaches the grader.
  • You can submit as many times as you like. Your best score stands, and each attempt tells you which checks passed so you can work the gaps.
  • Scored something you believe is correct? Use Report an issue on this page — that is exactly how the grading fixes in the changelog got found.

Create a free account to submit your lab for grading.

Create a free account
Found a problem with this lab?

Please sign in to report a problem — tying it to your attempts lets us reproduce and fix it faster.