DHCP Reservation (inactive)

Posted on 2010-09-02
Last Modified: 2012-08-13
In our DHCP list we have 'many' instances of inactive reservations. Is there a way to list / export when the reservation was last used? I intend to then go through & check which instances are still being used [static assigned IP Address] and delete any that are not active, anyone know of a quick & easy [not manually pinging each address] way to do this?

Question by:WGMIT
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Expert Comment

ID: 33590220
I'm someone else probably has a better way but if I made one up... I would:

Use something like AngryIP Scanner to scan the range (more like ping the range) I wanted for alive hosts and cross reference that with the inactives.

The result would be... If the host responds, yet has an inactive reservation for the same IP, then it would lend to it being static and warrant a quick look to be sure.

Author Comment

ID: 33590529
Thanks for the reply, but I am really needing something that can tell me how long the reservation has been inactive for; 2 weeks maybe someone is on holiday, 2 years maybe its not there anymore!!

Accepted Solution

BDoellefeld earned 50 total points
ID: 33590752
Oh, I see.

It will keep one week of logging history by default, the rest is vapor.

Logs are located here by default WINDOWS\system32\dhcp
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Expert Comment

ID: 33594067
Yes, perform an ANGRYIPSCAN. This will ping the entire subnet for you and also list the computer name of active pings.
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Expert Comment

ID: 33594090
Oops, didn't read what the recommendations were. You should also know that an inactive reservation means the IP address hasn't been offered to a client or server that it was designated for. So, you can rid yourself of ALL inactive reservations.....


Author Closing Comment

ID: 33617978

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