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After running for a month or so the svchost.exe that contains the DHCP as well as DNSCache services is showing a Mem Usage of above 400M in task manager. My network interfaces are all static IPs and not running a DHCP server so I'm guessing the usage is from the DNSCache.

Is there any reason that the memory usage for this process should be so high? I still have over a gig of free memory but I don't want to be worrying that if I need a lot of RAM at short notice (which does happen on these servers), that I'll run out. Maybe svchost is smart enough to give memory back under pressure but should I count on that?

From ipconfig /displaydns the cache itself only has around 64 entries so it can't possibly need all that RAM can it?

Edit: I wanted to add a note that while the below answer is useful, it did not fix my problem. My problem is specific to either the DNSCache (dns client) or DHCP (dhcp client) services. The below hotfix is for DNS Server memory leak.

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1 Answer

From:

http://msmvps.com/blogs/acefekay/archive/2009/09/03/the-dns-cache-poisoning-vulnerability-microsoft-kb953230-patch-and-ports-reservation-explained.aspx

You will want the hot fix for the hotfix :) http://support.microsoft.com/kb/975830/en-us

DNS Process Memory Leakage After Installing Hotfix 941672 for Windows 2003
If your DNS server is experiencing a large amount of memory being consumed by the DNS process to the point it hangs the DNS service and it stops responding, it may be associated to hotfix 941672. If 941672 was installed on the DNS server, 
there is a known memory leak issue in the DNS process associated with this hotfix. The issue has been fixed by installing hotfix patch 975830.

Please read more about it in the following link, where you can also request the hotfix.

The memory usage of the Dns.exe process keeps increasing after you install hotfix 941672 on a computer that is running Windows Server 2003 SP2 and that has the DNS server role installed
Article ID: 975830 - Last Review: October 27, 2009 - Revision: 1.0
http://support.microsoft.com/kb/975830/en-us

DNS Memory Consumption Related Discussion:
http://social.technet.microsoft.com/Forums/en-US/windowsserver2008r2general/thread/bcf3ac92-3485-4a2d-9386-55f2dcbc78f8

If you feel that you need more information to determine if a DNS process leak is occuring, you can enable debug logging, and use the following link in conjunction with the symptoms explained in KB975830 to further analyze the issue. Read the following link for more info.

DNS: Monitoring Server
http://technet.microsoft.com/en-us/library/cc783975(WS.10).aspx
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Looks like this is probably it. I won't be able to really test before bounty is over since takes so long for memory usage to grow. So unless something else comes up I'll accept this answer soon. –  thelsdj Oct 13 '10 at 4:59
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