Symptom
A client can't renew it's DHCP lease. The binding table, "show ip dhcp binding" may be stuck in "Selecting" state.
Conditions
- Must be using IOS or IOS-XE as a DHCP server.
- Must be using "remember" keyword under "dhcp pool" config
- When there is an IP Address conflict, there will be a "%DHCPD-4-PING_CONFLICT" in the logs. That IP can no longer be allocated, even to the host that had an active lease and is just trying to renew.
Workaround
clear dhcp binding with "clear ip dhcp binding "
Further Problem Description
The problem isn't the conflict per se, it is that the DHCP Server thinks it's still in the process of checking for a conflict, even though it isn't actively sending probes any longer.
