VLAN Troubleshooting Capstone: Native Mismatch & VLAN Drift

Bundle lab · $29.99

Advanced CCNA L2 troubleshooting in a compact branch. Some PCs can't reach their default gateway or other departments across two switches and a router-on-a-stick gateway, and your monitoring system has flagged a switching/trunking problem on the path. Validation is performed from the endpoints (Alpine hosts) using pings and ARP, and trunks are hardened with a non-default native VLAN.

Learning objectives

• Identify and correct access-port VLAN mismatches that break host connectivity
• Detect and remediate native VLAN mismatches on 802.1Q trunks
• Fix incomplete trunk allowed-VLAN lists to restore VLAN reachability
• Differentiate access vs trunk roles and convert links accordingly
• Validate segmentation using host-based tests (ping and ARP) and switch show commands
• Harden trunks with an intentional non-default native VLAN

Troubleshooting focus

• User access port assigned to the wrong VLAN (VLAN drift)
• Switch-to-switch trunk formed but native VLAN mismatch (CDP warnings)
• Trunk allowed VLAN list pruned incorrectly (required VLAN 20 missing)
• Uplink toward router mis-set as access, preventing ROAS subinterfaces from forwarding