CCNA Break/Fix: The Gateway Pair That Only Fails Over by Hand
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Lab 9 of 13 in CCNA Break/Fix II: Read the Symptom · ← Previous · Next →
CCNA exam domain: IP Connectivity
An office floor’s redundant default gateway pair keeps needing manual intervention. During an uplink outage the active gateway stays active and strands users, and when the repaired router returns it seizes the VIP immediately and the floor bounces. Troubleshoot the pair’s failover behavior by examining what each router monitors and when it is allowed to take the role back. Bring the pair into compliance with the convergence standard without changing anything else.
Learning objectives
- Diagnose why end hosts lose upstream reachability during a distribution uplink failure despite a redundant first-hop design
- Trace HSRP state transitions and compare them against the intended design for failure and recovery events
- Isolate which conditions a gateway should monitor to relinquish the VIP when it cannot forward upstream
- Distinguish recovery behavior that is immediate versus delayed to avoid churn and verify the intended hold-off is in effect
- Verify end-to-end reachability from the client during failover and controlled failback
Troubleshooting focus
- Users report that during a core uplink outage, the LAN’s virtual gateway remains up but off-net traffic dies until someone reboots or intervenes on a router.
- After repairs, as soon as the previously failed router returns, the floor momentarily drops again while the VIP flips back.
- HSRP shows an active/standby pair on the user VLAN, yet the behavior during failure and recovery does not match the intended design.
- The routers both define something to watch globally, but the HSRP decision on the user LAN does not appear to react to it.
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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.
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