DNS issues after 10.6.5 update

My fix actually returns dns handling back to the way it was in 10.6.4. Apple hasn't modified the
/System/Library/CoreServices/mDNSResponder.bundle since 10.6.0, only the 4 support files,
mDNS, mDNSResponder, mDNSResponder.sb and mDNSResponderHelper.

If you are still having dns problems, first try flushing the dns cache (terminal):
dscacheutil -flushcache

If you have a router, flush the cache by rebooting the router.

If still not corrected, replace dns servers with public dns servers:
pick one near you:
http://www.tech-faq.com/public-dns-servers.html
http://theos.in/windows-xp/free-fast-public-dns-server-list/
http://www.dnsserverlist.org/

Also, if you haven't upgraded to safari 5.0.3, do so, its much more stable. Be sure to clear
safari's cache if you experience problems or slow downs. Some users are having issues
with flash 10.1. Switching back to 10.0 r45 seems to help.
http://www.blogsdna.com/4329/how-to-uninstall-adobe-flash-player-on-windows-mac. htm
http://azlist.info/kj/mac/utilities/flashplayer10r45.zip

Running safari in 32 bit mode sometimes helps with stability issues.

Kj

Hello,

Thanks for your tips. But the problem is not Safari or Flash related. Nothing depending on DNS-service works anymore, when my problem appear. No "ping www.apple.com", no "nslookup apple.com", no surfing, nothing. But pinging an ip-address still works.

I switched to the google nameserver completely, even we have or own nameserver in the university environment.

I am sharing my cable network connection (en0) to my laptop (connected directly to en1 with the macpro <-- the one with the problem). When internet sharing is active the dns-hanging occurs much more often. When i disable internet sharing, the error occurs in mean only once a day.

But before 10.6.5 i never had problems with internet sharing.

any other ideas? thanks forward

If you are having total DNS failure in the apps, you need to downgrade to the mDNSResponder from 10.6.4, which is what the patches the poster above has provided. (In this problem scenario, ping/traceroute and even nslookup work fine. Just no DNS resolution in programs such as Mail or Safari or other applications that are using the broken DNS resolution library. The problem is that Apple broke mDNSResponder. Usually it starts failing when the CPU goes to sleep.)

If you are having a problem where only some domain names fail, but others work, then you have a different problem. Switching to using Google's DNS servers is said to alleviate this one.

Sounds like a mis-configuration problem.

Be sure both computers are not trying to share the same IP address.

Some router's DHCP doesn't play nicely with Macs. Setting network settings (properly) as
"Manually" or "Using DHCP with manual address" has been known to cure those
ills.

I had the same problem with my VPN after I updated my laptop to 10.6.5. I tried everything posted in this thread and nothing worked.

So I tried to connect to the VPN from other router and surprisingly it worked! Then I thought the router had something to do with all this mess. So I opened port 1723 (since my VPN use pptp) of the router and problem solved!

I hope it could help!

my macpro has a static ip address. the macpro share its connection over the second ethernet port using internet sharing. the macbook is connected to the macpro with its ethernet port. internet sharing make my macpro running a dhcp-server for the second (and only the second) ethernet port. so my macbook gets a ip address from the dhcp-server on my macpro.

everything should (and was before 10.6.5) be fine. but now, running internet sharing makes my mDNSresponder on the mac pro crashing, very often.

If there is a dhcp server issue in 10.6.5, my fix probably won't help that. I believe those services
are provided by different binaries than those included in the patch.

I suggest reinstall SL and update only to 10.6.4.

Kj

since my prior posting, i reinstalled 10.6.0, and then the combo
upgrade to 10.6.4 (not to 10.6.5) and then used the migration tool
to copy the user data.

this all worked perfectly. except i still have the symptom that
dns resolution still stops working randomly.

when i reboot, by the way (still the only way to resume operating)
when launchd sends the SIGKILLs to the various processes to shutdown,
it fails to kill both mDNSResponder and securityd on the 3 attempts it makes
prior to shrugging and rebooting.

as i've verified that i've got the right old versions of mDNS*, i'm now
forced to believe it's something in my user context or a new version of an app
i'm running which is tickling this behavior, and it isn't 10.6.5's problem
at all. still, i can't imagine any user preferences that have anything to do with
DNS resolution. i am running 10.6.4 (never applied the upgrade) on another
machine and have not experienced the problem). and since this happens
at random and apparently unrelated to what i do, app-wise, i'm mystified.

so my experience is similar to at least one other reporter here, who have applied
the installpackage to go back to 10.6.4 and had the same problem.

does anyone know whether:
- 10.6.6 beta has work in this area?
- does anyone have access to Radar and can see what bugs are filed on this?
- does anyone understand interactions between mDNSResponder and securityd,
and why would both be hung?

i am now tempted to try some experiments:
- create a new user (with a clean ~) and use it for all my app work.
this should determine whether it's the app mix or something to do with the
user context.
- start logging traffic through mDNSResponder...
- (wireshark)

i really don't need this tsuris (a technical term...)

"+i really don't need this+ tsuris"
tsu·ris also tzu·ris (tsrs, tsûr-)
n. Informal
Trouble; aggravation.

Thanks for the new 'word of the day'. I like it.

Back to your troubles;
Sounds like it might be a good ol' case of DNS Cache Poisoning:
http://www.csgeeks.org/~boyd/Misc/dns-cache-poisoning.html

Hey, its as good a guess as any. 😉

Yiddish spreads to SouthEast Texas 🙂

Just to add another data point to this discussion ... I had been experiencing total DNS failure after updating to 10.6.5 like many here have reported. This would occur at random intervals and required a reboot to correct. No amount of cache flushing or kill -9's would resolve the issue. Sometimes it took days to reoccur and other times it happened within a few minutes of rebooting. However, ever since rolling my DNS components back to the prior release per KJ's instructions, I have not experienced any more issues. It's been exactly one week now, a period of time that would have seen several reboots before making these changes and my MacBook Pro is back to performing flawlessly again.

Thanks for the tips and here's to hoping Apple addresses the issue in the next update.

DocBaldie,

I've tried flushing my DNS and using Googles DNS servers in an attempt to correct this issue, but nothing has worked. There are times when my internet just works, and there are others when it doesn't. I've tried applying the patch provided by KJK555 and that too has failed. Is there a way to verify that the files have been replaced by the patch? Restarting does nothing for me.

Symptoms:

Adium will not connect to MSN network using HTTP protocol (This is how I know net will probably not work as it should)
Able to go to news.yahoo.com but clicking on headlines times out.
Youtube.com times out.
This discussion thread does not load.

If I use Chromium or Firefox, I can sometimes do the above, sometimes.
I'm also able to connect to Astraweb and download at reasonably fast speeds

*Also, If I connect my Mac to another ISP (using ethernet) all these problems go away. Either my Airport card is bad, the WIRELESS ISP is screwing something up, or its OSX doing this. I've had the folks from the WIRELESS ISP come to my location to help me troubleshoot, and they were able to access all the sites I was having trouble with. They were running XP on their machines.

You, sir, are a GENIUS! I came here looking for answers to my DNS problems after updating to 10.6.5 and installed your packaged and it fixed the issue completely! No more DNS timeouts! I really hope Apple addresses this fix in an update soon but your patch works PERFECT. Thank you so much!

I had a DNS resolution problem with a single corporate-hosted application, and switching my network configuration to use Google's public DNS servers did the trick for me too.

I'm guessing that the problem has something to do with the topic of this article:

http://arstechnica.com/apple/news/2010/11/apple-fixes-broken-ipv6-by-breaking-it -some-more.ars

I've experienced the "total loss of DNS" issue. I can trigger it by connecting to a certain VPN service that I've set up. I can fix it with "sudo killall -9 mDNSResponder".

Prior posts have mentioned trying variants on the kill command, but you need 'sudo' and '-9' to really get mDNSResponder to restart.

You can see if mDNSResponder has really restarted by doing 'ps -ax | grep mDNSResponder' before and after your attempted kill, and comparing the pid (number in the first column). It should change.