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BeginnerPublished 2026-07-06

CCNA Foundations: OSPF Day 2 — Router IDs & Neighbor States

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Build a two-router OSPFv2 lab, assign deterministic router-ids using loopbacks, form a clean adjacency from Down through Exchange to FULL, and verify neighbor state and router-ids. End-to-end reachability is validated from real hosts across an enterprise-clean topology.

Track
Est. time
48 minutes
Difficulty
Beginner
Topics

Learning objectives

  • Configure OSPFv2 with deterministic router-ids sourced from Loopback0 addresses
  • Enable OSPF on specific interfaces using exact network/wildcard statements
  • Apply OSPF hygiene: passive-interface default, and selectively enable transit links
  • Observe and verify OSPF neighbor states and the peer router-id using show ip ospf neighbor
  • Validate end-to-end forwarding between hosts across the OSPF domain

Troubleshooting focus

  • No neighbors form: Confirm both sides are in area 0 with matching network statements on the 10.0.12.0/30 link.; Check show ip ospf interface Ethernet0/0 for hello/dead timers and MTU consistency.
  • Neighbor stuck in EXSTART/EXCHANGE: verify MTU matches on both ends of Ethernet0/0.
  • Routes missing: confirm loopbacks and LANs are advertised with exact wildcard masks; verify they are not passive-only if needed for adjacency (LANs should be passive but still advertised).
  • Host pings fail but routes look good: verify host IP/gateway, switch access VLAN on both switch ports, and that router LAN interfaces are up/up.

Topology

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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.

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