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Cisco ASA (used as dhcpd) - Is there a CLI command to release a previously assigned IP address?

My goal is to regain usage of a DHCP assigned address without  having to physically reboot the workstation or the ASA device.  Does anyone know if there is a CLI command to release a previously assigned IP address? The ASA is being used as the DHCP server.
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handsthompson
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handsthompson
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Hugh FraserConsultantCommented:
What platform is the workstation? If it's Windows, "ipconfig /release" will release the address. In linusx, "dhclient -r" would do the same.
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handsthompsonAuthor Commented:
Im sorry I should clarify that I do not have physical or remote access to the workstation.  I only have remote access to the ASA.
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Hugh FraserConsultantCommented:
I don't have access to a Cisco ASA, but I'll explain the problem with what you're asking.

Leases are issued by the server, and have an associated lifetime. The client will use that address (on the assumption that the server will not issue it to anyone else) until the halfway point in the lease's lifetime. At that point, the client will try to renew the lease. If it fails to contact the dhcp server, it will continue trying periodically until the lease expires, at which time the client will no longer have an IP address and stop transmitting on the network.

if it is able to contact the dhcp server, it will either renew its lease on the current IP address, or be given a new one.

But until this time, it will continue to use the original address. If you tell the dhcp server to drop the lease, the client won't know about it until it tries to renew. If the dhcp server then issues the address to another computer, you run the very real risk of having two machines on your network with the same IP address.
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