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IntermediatePublished 2026-07-02

DHCP: Verify Leases, Pools and Conflicts

Bundle lab

Hands-on IOS DHCP server practice focused on validating pool state, inspecting conflicts, and fixing a real address conflict caused by a legacy static host on the LAN. You will verify server-side leases and exclusions, observe a conflict entry, then permanently exclude the static IP and clear the stale conflict so a client can obtain a clean address.

Track
Est. time
45 minutes
Difficulty
Intermediate
Topics

Learning objectives

  • Configure and validate an IOS DHCP server with correct pool scope and options
  • Detect an address conflict using 'show ip dhcp conflict' and interpret detection methods
  • Permanently exclude a statically assigned IP to prevent future conflicts
  • Clear stale conflict entries and re-attempt client lease acquisition
  • Verify server-side state with 'show ip dhcp pool' and 'show ip dhcp binding', and client state from Linux (udhcpc, ip addr, ping)

Troubleshooting focus

  • Client fails to obtain a lease due to an active conflict entry
  • Pool statistics do not match expectations (exclusions vs. leased)
  • Client gets an address but cannot reach the gateway (check link, ARP, and default route learned by DHCP)
  • Misread of 'show ip dhcp binding' vs 'show ip dhcp conflict' leading to wrong conclusion

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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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