We have Windows 2008 Servers running and providing DHCP and DNS Services to the network. So far everything is working great.

The problem is, the clients which are provided with IPs from DHCP are automatically listed in DNS with their respective hostnames. Clients are listed 2-4 times with the same name but different IPs. There is always one right IP/hostname combination and 2-4 outdated one.

Is there any easy automated way to get rid of all the outdated ones? I assume there must be some way of making an expiration time in the DNS when outdated records get purged?


Yes, you can change the aging settings as in the screenshot. Expand the domain in the left column, right-click and go to properties, then from the general tab, click aging. From the help file:

No-refresh interval Specifies an interval of time, in either days or hours. When a resource record is refreshed, it is not refreshed again until this interval of time has elapsed.

Refresh (interval) Specifies the minimum time that records are expected to remain in the DNS database after the no-refresh interval expires.

This interval should not be smaller than the maximum refresh period for any resource records. In most networks, this interval corresponds to the Dynamic Host Configuration Protocol (DHCP) lease renewal interval. For DHCP servers running Windows Server 2008, the default lease renew interval is four days.

In other words, if you set it too low, without DCHP trying to renew its settings, there is no way for a client computer to automatically re-register the DNS.

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  • Thanks for the hint but this does not solve my problem. DHCP is set to 1 day lease time. DNS is set to 1 day. But I still have tons of outdated records. I'll check up on this on Monday... – Layticia Jul 15 '11 at 12:03
  • @Layticia To be honest, a one-day DHCP lease is not a good idea in the first place. It is the reason you have all these outdated records in the first place. Is there a special reason it is set so low? How big is your network? technet.microsoft.com/en-us/library/cc780311(WS.10).aspx (search duration). conferences.sigcomm.org/imc/2007/papers/imc17.pdf – KCotreau Jul 15 '11 at 12:13
  • This wasn't set by me and I haven't questioned it. I'll set this to 20 days now for both DHCP and DNS Aging and let this run for a bit and report back here with results... – Layticia Jul 15 '11 at 12:24
  • @Layticia You also have to right click your DNS server in the DNS console, go to Properties>Advanced and set your server to automatically scavenge each day for the above to work. – HostBits Jul 15 '11 at 12:29
  • @Layticia Set the DHCP back to default of 8 days. DHCP client check in at 1/2 the time, so it checks in with the DHCP server after 4 days if set to 8. I think checking in after 10 days may not be best either. You can then tell it cavange at a time slightly longer than that. – KCotreau Jul 15 '11 at 12:35

Have a read here for a detailed explanation of scavenging:



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