DNS.exe High Memory Usage

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Q. I did a fresh install of Windows 2008 R2 and my DNS memory consumption is going through the roof. If I reboot, it’s ok briefly, but then it goes up again. How can I stop it?

A. There are a lot of discussions about DNS high memory utilization on Windows 2008 R2 floating around. A lot of them point to disabling EDNS, which does not decrease the memory usage. The real problem is in fact due to the ports that DNS opens up: 2500 UDP IPv4 and 2500 UDP IPv6. This is a nice and round number for a busy production DNS server, however, for an internal DNS in a small office this is way too much.

To decrease the number of open ports, run the following command. For an internal DNS, with about 20 people in the office 100 ports is more than enough:

Dnscmd /Config /SocketPoolSize 100

Once command executed, restart DNS service – memory consumption should decrease.

You can also view how many ports you have open:

Dnscmd /Info /SocketPoolSize