Occasionally on one of my web servers svchost.exe runs around 60-80% running the DNS Client Service. This is on a Windows 2008 Web Server machine (patched up all the way) handling around 10M page views a day and around 5M unique users monthly.
I sometimes see it running on one of two servers in my farm, while handling the same amount of traffic as the other machines so I think it might be okay to disable it… Keep in mind that a server affected by it running close to 90% CPU while the others at 15%.
Now I know it caches the name resolution data but does it need to do it at this expense? I did some research and there are split recommendations on this so here I am asking you guys 🙂 Thanks!
Here are screenshots of the CPU utilization:
Best Answer
Disabling the dns client service will not disable dns lookups. The stack will still know how to do a dns lookup. Don't believe it? Try it.
Now, one possible cause of high dns query rates on your web server may be dns lookups related to logging of http requests. Disable logging of the client request source by dns name.