We have a secondary DNS server and we've been noticing that the DNS.exe process is getting rather large. (Like, rebooting the server large.)

I read something somewhere that 2k3 has two relevant memory leak issues, one is the DNS (supposedly fixed in Windows Server 2008), and another for DHCP.

DHCP is running on this server, but I don't see why. Hence my question. Is the DHCP client service required for (secondary) DNS to function?

Server has: 24 cores (X5650), 8GB RAM

-- edit -- It's worth adding that AD is not installed or relevant to this issue

-- edit 2 -- It is actually the DHCP Client service that is in question here. I didn't realise this at the time of posting. (Lesson: check everything yourself too)

  • Have you checked to see if a DHCP scope is configured on the server? If there is are there active leases? It could be that this server is "load sharing" the DHCP service with another DHCP server, providing for ip connectivity if one or the other server fails. This is a fairly common configuration for DHCP. – joeqwerty Nov 14 '12 at 4:18
  • I would be surprised, as it's in a Data center, and I would have thought nothing would be permitted via public IP, and everything is static on the private IP. But I'll have a look... :) – Mark Nov 14 '12 at 5:04
  • 3
    Server has: 24 cores (X5650), 8GB RAM ... Uh ... I hope you don't mind my pointing out that this is a colossal waste of server resources. Both in that you're using something this powerful for DNS and in that you're running Server 2003 on it. If I can set you up a screaming DNS server on an old HP G4 I have lying around, can I give this box a good home, and a job more suited to its capacity? – HopelessN00b Nov 14 '12 at 7:36
  • Haha. Yes, it's primary role isn't DNS, that's it's secondary role. It's Main Role is a mail server (on PHP, funnily enough) – Mark Nov 14 '12 at 22:14

No. DHCP is not needed for zone transfer, if that is what you are asking.

Reference: MS Support article: HOW TO: Configure a Secondary Name Server in Windows Server 2003. There is not a single reference of dhcp at all.

  • It says in the services, that DHCP is required for the secondary DNS to update. This seems strange to me, hence why I'm here. – Mark Nov 14 '12 at 5:06
  • You need one DHCP server to update dynamic dns record. Is that your only/primary dhcp server? Or are you using/serving dhcp service at all? – John Siu Nov 14 '12 at 5:14
  • Not using DHCP at all, so far as I'm aware... and I should be aware of it ;) My initial response was "turn it off", but my co-worker said the above. – Mark Nov 14 '12 at 6:02
  • @Mark Added a MS Support reference for you. – John Siu Nov 14 '12 at 6:49

DHCP server service is not required on W2k3 secondary DNS server. Secondary zone on secondary DNS is merely a copy of a primary zone that is hosted on another server, and DHCP doesn't make changes to this zone directly. If DNS dynamic updates are enabled in DHCP, it means all updates will be made to primary zone. Secondary DNS will query primary DNS for changes, compare serial number and will update itself if necessary.

Secondary DNS and DHCP can both reside on different machines with no problems.

Review this article Planning DNS Servers for DNS server capacity recommendations.

Have you checked if you have these MS07-062 or MS08-037 updates installed which can cause memory leaks? This is known issue. See link below >>

On a Windows Server 2003-based computer that has the update from security bulletin MS07-062 installed, you may experience a memory leak in DNS.


Clear the DNS cache on your server and see if the process size drops. You might have something filling it up with bad, random queries. Keep in mind that DNS does negative caching in that unresolved queries are cached for the duration of the SOA TTL.

  • (I'll assume you don't mean client /flushdns, but the DNS-server-y one.) – Mark Nov 14 '12 at 22:31

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