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DNS issues after 10.6.5 update

Since updating to 10.6.5 (via the combo update), I experience strange DNS problems on my laptop.

After working fine for some time, suddenly no DNS names are resolved any longer.
Looks like mDNSResponder simply died.

- This happens simultaneously in Firefox, Safari & even from the Terminal.
- It happens both on ethernet, and on wifi.
- I can still Ping my DNS servers, and I can ping my machine from remote as well.
- Everything where I can still remember the IP address seem to work fine.
- Problem happened in different networks
- Nothing obvious in the console messages

It really looks like a pure DNS problem, not a network issue.
Even the Windows emulation I sometimes run on that machine keeps working and can still resolve DNS names correctly.

I repaired permissions, reinstalled the update, cleared the DNS cache... the usual.

Until now, nothing solved the problem. I need to reboot, to get dns lookup back.
This will then work for some time (in the order of hours) and suddenly I'm stuck again.

cheers

Martin

MacBook Pro 15" i7, Mac OS X (10.6.5)

Posted on Nov 14, 2010 2:48 PM

130 replies

Nov 30, 2010 9:10 AM in response to Martin Jaekel1

For now I didn't noticed any solution floating on the web.
I always have terminals opened on my desktop, I'm getting used to flushing my DNS cache when I got an issue using the following handy shortcut (everything then works as expected for a while) :
alias flushdns='dscacheutil -flushcache'

Nov 30, 2010 9:53 AM in response to DocBaldie

I reinstalled the OS and upgraded to 10.6.4 and stopped. All worked well. I decided to complete the upgrade and am still not experiencing any problems. If the troubles return I'll go back to 10.6.4 and stay there until and if Apple resolves the issue.

rgev1973

Level 1

53 points

Nov 30, 2010 1:03 PM in response to Martin Jaekel1

Dear all,

could you check if you got LittleSnitch installed?
If yes, which version?

I removed some software - but updated LittleSnitch as well. IMHO this could have been the issue.

Nov 30, 2010 1:17 PM in response to rgev1973

I have LittleSnitch v2.3 installed. I tried disabling LS and still saw mDNSResponder crash, so I don't think it is related to LS. I've also been running LS since 10.6.0 and have not had this problem until the 10.6.5 update.

Message was edited by: DocBaldie

KJK555

Level 4

2,900 points

Nov 30, 2010 3:15 PM in response to DocBaldie

Here is the fix;

You will need the following files:

/usr/share/sandbox/mDNSResponder.sb
#from original SL DVD 10.6.4 or earlier#

/usr/sbin/mDNSResponder
/usr/sbin/mDNSResponderHelper
and
/usr/bin/mDNS
#from 10.6.4 update#

I used Pacifist to install (replace) them from 10.6.4 combo update
and original DVD.

So far so good, in fact activity monitors shows a bit less cpu usage at idle
after installing them. DNS now stable.

KJK555

Level 4

2,900 points

Nov 30, 2010 9:59 PM in response to DocBaldie

I have created an standard install package to make the fix painless to apply.

You can get it here:
http://azlist.info/kj/support/mdns_repair10.6.5.pkg.zip

unzip it to your desktop and install the package.

note: for installation on 10.6.5 systems only.
#replaces the four files described in my previous post#

Dec 1, 2010 6:52 AM in response to KJK555

Awesome! Thanks.

Also, for anyone not comfortable with replacing system files...I don't know how or why but I've been sampling mDNSResponder with 'top' in the terminal and it hasn't frozen for me in 2-3 days now.

In the terminal I use:

ps ax | grep mDNS
(this gives me the pid of mDNSResponder, in my case, 24)

then:
top -pid 24

I just hid the window and went about my business.
Anyone want make a guess as to why this is working? Coincidence?

KJK555

Level 4

2,900 points

Dec 1, 2010 9:04 AM in response to virtualsnyper

I wasn't experiencing total dns failure like some folks were. I was experiencing slowdowns on
loading websites, particularly on those sites that my adsweep filter was working the hardest.
Some pages were taking 30 seconds or more to load and Safari was unresponsive until they
loaded completely. My itunes internet radio would cut in and out intermittently also until I
cleared the dns cache. Clearing dns cache would help, but not cure the problems.

After applying the fix, all the above problems went away. The same pages that took 30 seconds
to load, loaded in about 10 seconds and Safari was still responsive even while the pages were
loading. Other pages that had few ads would load instantly, and my itunes internet radio works
flawlessly again. Some web pages that wouldn't load before, will now load.

Don't worry folks, I am confident Uncle Steve will get 'er fixed soon. In the meantime, this little
patch should get you by.


Dec 1, 2010 9:56 AM in response to KJK555

Thanks KJK555 - I can confirm that your solution works for me.

I used to find Mail.App and Safari would fail to resolve addresses after a wake from sleep (intermittently). I used to kill mDNSResponder to resolve the issue.

Interestingly this issue only occurred on my iMac, but not my Mac mini or my Macbook.
The former has the more complex environment including VMWare Fusion and Little Snitch.

KJK555

Level 4

2,900 points

Dec 1, 2010 2:29 PM in response to Michael Rourke

Thanks for the feedback Micheal:

Maybe the DNS problem has something to do with third party software conflict. My Mac Pro
has VMware Fusion and Parallels Desktop installed. I did have little snitch installed, but
I removed it several months ago.

Kj

Dec 2, 2010 12:59 AM in response to KJK555

I set up a brand new iMac at work today. Did not use migration assistant. Same DNS issue occurred - after coming out of sleep. The only 3rd party apps that had been installed at the time were Firefox, Chrome and MenuMeters. So looking rather less likely to be caused by a 3rd party app.

Dec 4, 2010 7:58 AM in response to Martin Jaekel1

The fix, worked well for me.
I have 3 different VPN entries and now I can connect/disconnect without restart or hangs.

Hopefully Apple will solve this with a patch.

Thanks again,
AA

Dec 6, 2010 2:55 AM in response to KJK555

To bad. This fix didnt help me. I still have the **** dns problem.

Mr Mario

Level 1

0 points

Dec 6, 2010 10:22 PM in response to ingmar.ev

Your fix didn't work for me either. This is weird. I'm not much of a networking guy, so I may be having some other issue, but it sounds like I have the same problem everyone else has been having on this thread. Some sites work fine, but other sites, like yahoo news fail to load whenever I click on an article. I'm also able to download from usenet without a problem. This is the first time in the two years since I've owned this laptop that I've had any issues. I wish I could go back to 10.6.4. 😟

Dec 7, 2010 7:15 AM in response to Mr Mario

Mario, there are 2 fixes listed in this discussion.

1. Manually set DNS to use Google's DNS servers - this sounds like the fix you need.

2. Apply patch or replace mDNS files (mDNS, mDNSResponder, mDNSResponder.sb, mDNSResponderHelper) with copies from a working 10.6.5 install. - this is not the fix that you require, based on your posting.

Good luck.

DNS issues after 10.6.5 update