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CCNA: Pruning the Allowed VLAN List on Trunks
Hands-on CCNA lab focusing on 802.1Q trunk allow-lists. Build a realistic three-switch campus with two user hosts in VLAN 10. First bring up trunks carrying all VLANs by default, then implement an explicit allowed VLAN list and prune a non-used VLAN. Intentionally remove VLAN 10 from one trunk to observe an outage, verify with Linux pings and IOS show commands, and restore service by fixing the allow-list. Reinforce native VLAN alignment and compare default vs explicit trunk policy.