I was messing around with the Desktop Experience on my Windows Server 2008 R2 server and decided that I wanted to use one of the gadgets that I found useful with Windows 7. The gadget shows all of the core processor usage and the memory usage on the server.
This was a domain controller in my R&D farm, it is also my Hyper-V host so I kind of use it as a workstation as well. Don't judge me...
I installed it and found that my memory usage was abnormally high. Investigating, I opened Task Manager and found that DNS was eating up about 35MB per core. What the??? DNS should be nearly non existent. So I started to do some checking.
I hooked up my handy dandy Colasoft trace tool and found that I got a ton of errors when trying to connect to my ISP's DNS. Something about wrong format, more specifically "Additional Record: of type OPT on class Unknown DNSClass". Failure after failure after failure. It was literally like my DNS service was caught in some sort of infinite loop. What is this noise?
I found out that Microsoft was trying to be proactive with Server 2008 R2, and, by default, they enabled a new DNS format that hasn't quite yet been adopted by everybody yet. Like IP V6, this format, EDNS, is not yet everywhere. Bad news for me, because it was causing me pain.
I really don't have a whole lot of experience with DNS, other than adding records and whatnot, so how to disable this EDNS?
I found on TechNet there is a little tool, dnscmd, that will do the trick. So, all I did to disable it was to run dnscmd /config /EnableEDnsProbes 0
Immediately, my memory dropped from 35MB per core to about 2MB total. ColaSoft reported no new format errors. For now, it seems as if EDNS is not yet ready for the real world.
No comments:
Post a Comment