IntermediatePublished 2026-07-22
CCNA Foundations: DHCP Snooping — Trust the Right Edge Ports
Archive lab
CCNA exam domain: IP Services
Harden the access layer against rogue DHCP servers by enabling DHCP snooping on an L2 access switch and trusting only the legitimate server-facing port. You will validate that client access ports remain untrusted and that rogue DHCP offers are dropped while legitimate offers are permitted.
Learning objectives
- Explain how DHCP snooping protects against rogue DHCP servers at the access edge
- Enable DHCP snooping globally and for the user VLAN on a Cisco IOS L2 switch
- Designate only the server/uplink-facing port as trusted; keep client-facing ports untrusted
- Validate the behavior with show commands and a host-side DHCP request
- Relate legitimate vs rogue DHCP offers to snooping trust state
Troubleshooting focus
- Clients fail to obtain leases when snooping is enabled but the correct server-facing port is not trusted
- Rogue DHCP server offers are blocked only on untrusted ports in VLANs where snooping is active
- Snooping is inert if not enabled globally and per-VLAN
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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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