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Multiple DNS entries with same IP address

When viewing my DNS entries, I am seeing multiple machines having the same IP address.  Is this because my lease period in DHCP isn't long enough?

Mike
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Chris Dent
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Hi Mike,

Do you have Aging and Scavenging configured on there?

If not, it's common to find duplicate entries after a while in DNS as they don't get discarded when a client is done with them. It's something that's more noticable with a Short Lease as clients end up with new IPs much more often.

Aging Intervals are set in the Properties for each zone you want to keep tidy (AD Integrated with Dynamic Updates enabled). You will also need to tick the little box at the top.

Generally it works best to setup the two Aging Intervals (No-Refresh and Refresh) to match up with your DHCP Lease Time when you add them together.

So, the default values, 7 Days each, work well with a 14 Day DHCP Lease Time.

You wouldn't want to set Aging Intervals any less than 1 Day Each (2 Days in total) or you will find Service Records for your DCs are Scavenged.

Once the Aging intervals at set one DC in your Domain should have Scavenging Enabled and set to a Period of 1 Day in the Advanced Properties for the DNS Server.

That means each day your server will go out and clear out records where the client hasn't checked in for the full duration of both of the Aging Intervals.

I hope that all makes sense!

Chris
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csg_int_it

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Chris,
On our main DNS zone, I have set each the No-Refresh and Refresh intervals to 7 days.

Also, I have set the Scavaging Enabled interval to 1 day.

Let me know if I understood your instructions.

Mike
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Chris Dent
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Chris,
I know I accepted the wrong solution but I figure the people who use this service are bright enough to go through the thread.

Thank you for your prompt response to my question.

Mike

You're welcome :) I'm sure they'll work it out, and if not I'll probably still be hanging around the area.

Chris