AdvancedPublished 2026-09-25
CCNA Break/Fix: Routes Configured, Never Installed
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Lab 11 of 13 in CCNA Break/Fix II: Read the Symptom · ← Previous · Next →
CCNA exam domain: IP Connectivity
Troubleshoot a dual-stack hub-and-spoke where IPv6 traffic never flowed after go-live. IPv4 works end-to-end, but IPv6 static routes are present in running-config and missing from the RIB. Compare configured vs installed routes, trace next-hop reachability per link, and correct the next-hop so each static becomes active. Validate from the user LAN.
Learning objectives
- Diagnose why a configured IPv6 static route is absent from the routing table
- Compare static route configuration against interface addressing and neighbor reachability
- Trace IPv6 forwarding from the end host and isolate where traffic stops
- Distinguish working IPv4 control paths from broken IPv6 data paths during dual-stack incidents
- Verify the repaired state using host-driven tests and device route tables
Troubleshooting focus
- IPv6 pings from the branch user LAN fail to HQ and the other branch while IPv4 succeeds across the same path
- Configured IPv6 static routes exist in running-config but do not appear in show ipv6 route
- No IPv6 packets captured or counters incrementing on the expected outbound interface
- Traceroute6 from the host halts at the first hop or reports no route to host
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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.
- 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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