CCNA Break/Fix Capstone: One Floor, Two Layers, One Ticket

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Lab 13 of 13 in CCNA Break/Fix II: Read the Symptom · ← Previous

A full-path break/fix capstone for CCNA troubleshooting. A single floor was renumbered and re-cabled. Users on that floor cannot reach anything — not their default gateway, not other subnets, and not the internet. The change record mentions both the access switch and the internet edge. Your job: prove the path hop-by-hop from the client outward and repair every break. Fixing only one side does not change the symptom; both layers must be corrected.

Learning objectives

• Diagnose end-host reachability by walking the path from access switch to WAN edge and beyond
• Trace VLAN membership against the intended design and distinguish a L2 mismatch from a L3 routing fault
• Isolate default route issues on a branch router versus return-path issues on an edge router
• Compare NAT translations against expected inside/outside boundaries and the egress interface used
• Verify the repair from the client perspective and confirm that both the campus path and the internet path are restored

Troubleshooting focus

• The floor cannot reach its default gateway reliably — determine whether the host is in the intended VLAN and whether the gateway is in the same broadcast domain.
• Traffic doesn’t leave the site — verify the branch’s next hop is on-link over the correct transit and that the default is actually installed.
• Traffic that does leave the site has no return — validate the edge’s route back to the floor and ensure NAT overload uses the correct egress interface.
• Only device-to-device pings succeed — prove the issue from the end host, not only between routers; a router-to-router ping can hide host-facing faults.