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Svchost.exe/DNS Client [DNScache] Using 99% CPU


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#1 xblindx

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Posted 29 July 2009 - 12:55 PM

Hi, for the past month or so, whenever I open my browser, it takes around 30 seconds for the homepage to load (no programs that use the internet will work at this time) and I check task manager and notice svchost.exe (the network service one) is taking up 99% of my CPU. Once my homepage loads, pages after that load normally, but occasionally it will happen again. I checked process explorer and found that it is DNS Client [DnsCache] that is using all of the CPU whenever this happens. Should I simply disable the DNS Client service? I don't know what exactly it does, but I have seen some people use it as a fix, but I would like to know your expert opinions :thumbsup:

Edited by xblindx, 29 July 2009 - 12:56 PM.


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#2 hamluis

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Posted 29 July 2009 - 01:03 PM

Seems that you can't hurt anything by disabling it, http://www.theeldergeek.com/dns_client.htm

Louis

#3 xblindx

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Posted 29 July 2009 - 01:28 PM

What does this part mean " If this service is stopped, this computer will not be able to resolve DNS names and locate Active Directory domain controllers." I read the real world answer too and don't quite understand it.

#4 hamluis

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Posted 29 July 2009 - 04:47 PM

The key line is the next one: Is this service needed? No.

Heck, if I spent all day researching technical phrases I don't understand...I probably should have been a coder or something other than what I am :thumbsup:.

The "No" was good enough for me, I believe them when they say that it's not worth considering.

Louis

Edit: This is not my professional line of work, so I don't evidence a professional approach to understanding or working with computers :flowers:.

Edited by hamluis, 29 July 2009 - 04:48 PM.


#5 xblindx

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Posted 29 July 2009 - 10:46 PM

Well I disabled it, and everything seems to be running smoothly now, thanks for the advice :thumbsup:

#6 hamluis

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Posted 30 July 2009 - 09:50 AM

Easily done, happy computing :thumbsup:.

Louis

#7 Andrew

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Posted 30 July 2009 - 10:09 AM

The DNS resolver service caches DNS lookups so that the system doesn't have to perform a new lookup every time you visit a website. Disabling the service means that Windows will always query your default DNS server when you visit a website. While disabling it will add some additional overhead to your Internet usage it ought not make a noticeable difference while browsing the web.

#8 hamluis

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Posted 30 July 2009 - 10:24 AM

Thanks, AA :thumbsup:.

Louis

#9 xblindx

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Posted 02 August 2009 - 10:54 AM

The DNS resolver service caches DNS lookups so that the system doesn't have to perform a new lookup every time you visit a website. Disabling the service means that Windows will always query your default DNS server when you visit a website. While disabling it will add some additional overhead to your Internet usage it ought not make a noticeable difference while browsing the web.


I'm guessing this is because of the above, when I open facebook/myspace pages, it takes a bit longer to load, not really noticable but I was just wondering if this is why?

#10 aommaster

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Posted 02 August 2009 - 11:01 AM

And in addition to xblindx's question, is it the cache what you clear when you run ipconfig /flushdns?
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#11 Orange Blossom

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Posted 02 August 2009 - 12:17 PM

In answer to aommaster, yes it is.

I disabled the DNS cache service too. I manually connect to the internet, and when the connection was made, my CPU would spike up to near 100% for 4 minutes or longer plus tie up my internet connection for quite some time. (I'm on dial-up).

HJT Team Coach Carolyn provided the answer: I have a large hosts file, MVPS+ additional entries. Because I have that installed, the DNS cache service should be disabled if on Windows 2k or XP because it makes the computer very slow. I don't know about Vista or other OS's.

From what galadriel told me, what happens when you disable the DNS Cache service is that your computer will have to query your ISP DNS service to resolve the addresses. If that service should go down, you could use the Open DNS service instead.

Orange Blossom :thumbsup:
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#12 aommaster

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Posted 02 August 2009 - 01:36 PM

Thanks Orange Blossom!
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#13 CoolCatBad

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Posted 02 August 2009 - 01:38 PM

This problem usually results from a huge HOSTS file, some anti-spyware and ad-blocking techniques can lead to a HOSTS file approaching 3MB or more, which means DNS lookup is a crippling CPU task.

#14 Clothahump

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Posted 13 August 2009 - 09:59 AM

Seems that you can't hurt anything by disabling it, http://www.theeldergeek.com/dns_client.htm

Louis

I stumbled over this page while researching the same problem: SVCHOST was eating up 50-80% of the CPU every time I rebooted. I read this, disabled it, rebooted and voila! No more problem.

Thanks, guys!

#15 hamluis

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Posted 13 August 2009 - 12:12 PM

Nice self-help, happy computing :thumbsup:.

Louis




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