DHCP Pool: Excluded Range Exhaustion
A correctly sized DHCP pool hands out nothing at all. Diagnose the excluded range and fix it yourself, live, right below.
Symptom
The binding table is empty, but a /24 pool has only four addresses available. Find the reservation that consumed the scope.
Your mission
Prove the cause, then fix it
Format
Guided CLI investigation
Investigate before you configure.
Use the CLI evidence to isolate the fault, make the smallest safe correction, then verify the network state changed.
Observe the symptom and link state.
Diagnose by comparing the protocol evidence.
Verify the expected device state and confirm the original symptom is resolved.
Console access: R1
This workspace stacks for portrait phones. Rotate to landscape for the full split-screen console.
Need a hint?
Reveal the root cause when you're ready.
Try the investigation first, then use this as your escape hatch, not a dead end.
Lab debrief
Turn the session into a repeatable troubleshooting pattern.
Use this reference after your attempt: first explain the symptom, then verify the evidence, then confirm the repair.
The problem
New clients cannot lease addresses from the 10.0.0.0/24 CLIENTS pool. The router reports almost no available addresses, yet show ip dhcp binding contains no active leases.
What you'll practice
- Interpret DHCP pool utilization and available-address counts
- Compare pool state with the binding table
- Inspect excluded ranges in running configuration
- Replace an overbroad exclusion safely
- Verify that infrastructure addresses stay reserved while client capacity returns
The topology
R1 is the DHCP server for one /24 client LAN. Infrastructure uses the first ten addresses; the rest should remain available to endpoints.
Commands to run yourself
The real diagnostic commands for this lab, copy-paste ready. Run these in the same order to reproduce the investigation on your own session.
show ip dhcp poolshow ip dhcp bindingshow running-config | section ip dhcpTopology diagram
Frequently asked
Why can a pool be exhausted with no bindings?
Excluded addresses never enter the allocation pool, so they do not appear as bindings. An exclusion covering nearly the whole subnet leaves almost nothing to lease.
Why keep a smaller excluded range?
Routers, servers, and other statically addressed infrastructure still need protection from duplicate DHCP assignments. The fix narrows the reservation; it does not remove that safeguard.
Ready to run this lab yourself?
No setup, no image sourcing. Book a session or ask for a live demo.