CCNA Break/Fix Capstone: One Symptom, Two Faults

Today's daily lab

Advanced CCNA troubleshooting capstone: a user on VLAN 10 can reach the gateway but not a remote server. Two independent faults exist on different layers; fixing either alone does not restore end-to-end reachability. Diagnose the full path, implement the minimal, design-aligned repair on each device, and prove bi-directional traffic works.

Learning objectives

• Trace end-to-end forwarding across L2 and L3 boundaries using show and ping/traceroute tools.
• Validate router-on-a-stick design: subinterface tags vs. switch uplink trunking.
• Diagnose asymmetric routing and install the correct return path via static routing.
• Differentiate a symptom from its root causes; identify when multiple faults produce one user complaint.
• Prove the repair with both forward and reverse traffic tests from hosts, not just device-to-device pings.

Troubleshooting focus

• Users in VLAN 10 can ping their default gateway but cannot reach the server subnet across the router-to-router link. The failure persists even though local ARP and the gateway respond; the issue is not on the host. The operator sees one symptom; the path has more than one fault. Work hop-by-hop: confirm VLAN tagging on the switch uplink toward the router-on-a-stick subinterface, then confirm a return route exists on the remote router.