Recently I was trying to create a reservation for a MAC address in DHCP, Upon trying first I got an error “The specified address is not available”, I tried multiple times but was not able to create the entry even with a different set IP address. I re-validated the current reservation and leases but the specific Mac address isn’t listed.

Upon further investigation I found that this MAC is somehow mapped to another reservation and isn’t visible, in a way its lingering.

Here is what we did to resolve the issue

1) We took a dump of DHCP configuration using the following command


Netsh Dhcp Server Dump>Dump.txt

2) We searched the dump file for the problem Mac entry and we were able to find it.

PS: The Mac entry in GUI might show associated to a different Mac address, but we need to delete that in order to fix the issue

3) We went ahead and deleted that reservation from the DHCP database.

Now I was able to create the new reservation for the problem Mac.

Feel free to report any new issue on our forum to seek expert help

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An automobile enthusiast at heart and computer geek by profession, started my Career with MS in 2005.Left Jobs and started Pledge Technologies (the parent company to Grishbi) back in 2009.We have been providing IT consulting to various Small and Medium businesses across US and UK since then.Our company specialises in Microsoft Server technologies like AD, Exchange, the rest and with numerous Office 365 migrations under our belt, we quite an expert with that too. Whatever we learn in our day to day life, we share it back on Grishbi as a Thank for all the love and support our customers have given us.
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