L2 Security Troubleshooting Capstone: Trust Boundary

Bundle lab · $29.99

Advanced CCNP Layer-2 security troubleshooting on a single access switch. Diagnose and correct an inverted trust boundary that breaks DHCP and ARP validation: DHCP Snooping and Dynamic ARP Inspection (DAI) are enabled for VLAN 10, but the uplink is not trusted for DHCP and a host port is incorrectly trusted for ARP. Use show commands to find the issues, fix the trust boundary, and restore client connectivity without changing router/host configs.

Track

CCNA

Est. time

55 minutes

Difficulty

Advanced

Topics

CCNP, Switching, Layer 2 Security, DHCP Snooping, Dynamic ARP Inspection (DAI), Troubleshooting

Learning objectives

Interpret DHCP Snooping and DAI operational state using show commands to locate a misplaced trust boundary
Correctly place the trust boundary: uplink trusted, host access ports untrusted
Validate that DHCP Snooping builds a binding table and DAI enforces ARP validation against it
Restore client connectivity by fixing deterministic switch configuration only (no router or host changes)

Troubleshooting focus

Correlate DHCP failure symptoms (no lease) with DHCP Snooping trust on the uplink
Correlate legitimate ARP drops with DAI enforcement and missing/incorrect trust placement
Leverage show ip dhcp snooping, show ip dhcp snooping binding, show ip arp inspection, and show running-config interface to triangulate the boundary

Topology

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What's included in the package

Work / baseline CML import — lab-work.yaml
Topology diagram — topology.svg
Print-ready topology diagram (PDF) — topology.pdf
Step-by-step learner guide (Markdown — for Obsidian/VS Code) — lab-guide.md
Branded PDF lab guide — open in any viewer (Adobe/Preview) — lab-guide.pdf
Getting-started README — README.md
Verification checklist — verification-checklist.md

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L2 Security Troubleshooting Capstone: Trust Boundary

Learning objectives

Troubleshooting focus

Topology

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