Snow Leopard keeps dropping DNS

Joined
Jun 8, 2009
Messages
6
Reaction score
0
Points
1
Location
Henniker, NH
Your Mac's Specs
MBP (4,1) 2.5 GHz 4 GB 300GB OS X 10.5.6
I upgraded my iMac rev 5,1 from 10.5. The 10.6 install was flawless, but I lost name resolution for machines on my local network. I could ping Google, but could only ping local machines by IP address.

I went into my network settings and futzed around (changed IPv4 from DHCP to manual, then back to DHCP) and name resolution started working.

After a couple of hours, it stopped working again. Took the same steps mentioned above and it's working again.

Does anyone have any ideas as to how I might resolve this?
 

chscag

Well-known member
Staff member
Admin
Joined
Jan 23, 2008
Messages
65,248
Reaction score
1,833
Points
113
Location
Keller, Texas
Your Mac's Specs
2017 27" iMac, 10.5" iPad Pro, iPhone 8, iPhone 11, iPhone 12 Mini, Numerous iPods, Monterey
Try resetting your router. Some folks have reported intermittent problems connecting after a Snow Leopard install. Resetting the router seems to have solved the problem for most.

Regards.
 
Joined
Aug 29, 2009
Messages
1
Reaction score
0
Points
1
Location
South Wales
Your Mac's Specs
Mac Pro 2.8GHz Quad core xeons, 8GB/Mac Book Pro/iMac
I've also got this problem after upgrading my 3 Macs. Resetting the router has not solved it.

Connecting to my 2 Linux boxes in the Finder is as quick as it was under leopard but trying to connect to, or share the screen on the other Macs now takes about 2-3 mins.

There appears to be no DNS problems when running Win2008 server in Fusion!

Regards
 
OP
B
Joined
Jun 8, 2009
Messages
6
Reaction score
0
Points
1
Location
Henniker, NH
Your Mac's Specs
MBP (4,1) 2.5 GHz 4 GB 300GB OS X 10.5.6
Try resetting your router. Some folks have reported intermittent problems connecting after a Snow Leopard install. Resetting the router seems to have solved the problem for most.

Regards.

The problem seems to have cleared by itself. My *router* is an Ubuntu server. My iMac uses the Ubuntu server for its primary DNS and my firewall (ipCop) as its secondary. If the problem comes up again, I reboot both and report back.

Thanks for the suggestion.
 
Joined
Aug 30, 2009
Messages
1
Reaction score
0
Points
1
Problem appears to be related to primary vs. secondary DNS

I'm running the same setup; I have a Linux DNS server that serves out internal IP addresses for my own domains, and I have my wireless router configured to broadcast that as the primary DNS server, and my ISP-supplied DSL router as the secondary server.

Under Snow Leopard, almost universally, requests to my domains would end up getting the external IP address rather than the internal one. I deleted the secondary DNS server from my wireless router configuration, so that my Snow Leopard machines only get one DNS server supplied, the internal one. That fixed the problem, but it would be nice to be able to configure my backup DNS server again.
 
Joined
Sep 4, 2009
Messages
1
Reaction score
0
Points
1
Same Problem, Different Flavor

I am having the same problem. I upgraded my MacPro and my MacBook and they are both the same. My Primary internal dns is run off a xServe and secondary is my Smoothwall Firewall. I have restarted both, and the issue remains.
 
OP
B
Joined
Jun 8, 2009
Messages
6
Reaction score
0
Points
1
Location
Henniker, NH
Your Mac's Specs
MBP (4,1) 2.5 GHz 4 GB 300GB OS X 10.5.6
Reporting back...

After resetting my network settings for a second time on the iMac, it hasn't dropped DNS for 6 days now. Not sure why it took two tries, but it seems to be working.

Upgrading my MBP to Snow Leopard this weekend and will report back whether I have the same issues.
 

dtravis7


Retired Staff
Joined
Jan 4, 2005
Messages
30,133
Reaction score
703
Points
113
Location
Modesto, Ca.
Your Mac's Specs
MacMini M-1 MacOS Monterey, iMac 2010 27"Quad I7 , MBPLate2011, iPad Pro10.5", iPhoneSE
I've also got this problem after upgrading my 3 Macs. Resetting the router has not solved it.

Connecting to my 2 Linux boxes in the Finder is as quick as it was under leopard but trying to connect to, or share the screen on the other Macs now takes about 2-3 mins.

There appears to be no DNS problems when running Win2008 server in Fusion!

Regards

It takes my mac with Snow Leopard more like 2-3 seconds to share the screen here. That is with many other macs on the network and many PC's also. All connect very fast.
 
Joined
Nov 30, 2008
Messages
3
Reaction score
0
Points
1
I've seen this broken DNS situation on a number of machines upgraded to SL, on various kinds of home and corporate-style networks. It's definitely a bug in SL.

The symptom that I see is simply that a dig will work on a DNS name just fine, returning the proper IP address. However any other command that uses the DNS name (curl, ping, any GUI app like Safari, etc) will claim that the DNS name won't resolve. Obviously bogus and a bug.

I tried various things, including dscacheutil -flushcache, fooling with the network settings, Locations, etc, and some would provide a temporary workaround, usually with some disruption.

However, I happened across a Parallels support topic that provided what seems like a sure-fire workaround, either temporary or longer-lasting, until Apple fixes this bug.

The basic workaround is to issue the command sudo killall mDNSResponder at the Terminal prompt when this issue occurs, and all starts working properly.

The Parallels support article has steps to make it a permanent workaround if desired, until Apple fixes it: KB Parallels: Cannot resolve DNS names inside Mac OS X Snow Leopard Guest
 
Joined
Sep 9, 2009
Messages
1
Reaction score
0
Points
1
I noticed this same exact problem on my MacPro yesterday. It was never an issue before 10.6. Changing the ttl on the DNS server fixed it for me (not much help if you don't have access to do that).

Here's the deal - one of our networks at work had ttl's of 5256000 seconds. I had trouble browsing to web servers on that network. Most other addresses worked fine, but had much lower ttl's. I asked our DNS administrator to adjust the ttl on one problem address down to 604800 and suddenly the problem is gone (for that one address). Then I had him change all records to be no more than 604800 (an arbitrary number on my part, 7 days vs 60 before). It seems totally fixed.

If you're seeing this on a home network, check if your router is doing dns caching or anything like that. If possible adjust the ttl or turn off the DNS caching and see if that fixes it.

To check if maybe this is your problem, use Network Utility to lookup the name. You'll see a line like this:
myserver.me.com 43200 IN A 10.10.10.15
That 43200 is the ttl (time to live, in seconds). I know from experience that 5256000 is too high an causes problems in SL, and that 604800 does work. Where exactly it breaks I'm not sure.

I'm interested to hear if this fixes anyone else's problems.
 
Joined
Sep 22, 2009
Messages
2
Reaction score
0
Points
1
I noticed this same exact problem on my MacPro yesterday. It was never an issue before 10.6. Changing the ttl on the DNS server fixed it for me (not much help if you don't have access to do that).

Here's the deal - one of our networks at work had ttl's of 5256000 seconds. I had trouble browsing to web servers on that network. Most other addresses worked fine, but had much lower ttl's. I asked our DNS administrator to adjust the ttl on one problem address down to 604800 and suddenly the problem is gone (for that one address). Then I had him change all records to be no more than 604800 (an arbitrary number on my part, 7 days vs 60 before). It seems totally fixed.

If you're seeing this on a home network, check if your router is doing dns caching or anything like that. If possible adjust the ttl or turn off the DNS caching and see if that fixes it.

To check if maybe this is your problem, use Network Utility to lookup the name. You'll see a line like this:
myserver.me.com 43200 IN A 10.10.10.15
That 43200 is the ttl (time to live, in seconds). I know from experience that 5256000 is too high an causes problems in SL, and that 604800 does work. Where exactly it breaks I'm not sure.

I'm interested to hear if this fixes anyone else's problems.

Thanks for the hint. Same problem with my Macbook Pro after upgrade. Aside from sleep, applications will not resolve local domain hostnames after a few minutes after boot. Disabling and renabling DHPC in Snow Leopard would cure this problem until a few minutes later and same problem occurs.

Seems like Snow Leopard is not respecting DNS ttl value of 0 by not querying the DNS server? I use DNSMasq (in a dd-wrt router) and that is the ttl default for local domain hostnames. Use "dig myhostname any" to confirm. I modified DNSMasq ttl to 1 second by adding this option:
local-ttl=1

and I no longer experience this problem. I hope this information can help someone.
 
Joined
Sep 22, 2009
Messages
2
Reaction score
0
Points
1
Thanks for the hint. Same problem with my Macbook Pro after upgrade. Aside from sleep, applications will not resolve local domain hostnames after a few minutes after boot. Disabling and renabling DHPC in Snow Leopard would cure this problem until a few minutes later and same problem occurs.

Seems like Snow Leopard is not respecting DNS ttl value of 0 by not querying the DNS server? I use DNSMasq (in a dd-wrt router) and that is the ttl default for local domain hostnames. Use "dig myhostname any" to confirm. I modified DNSMasq ttl to 1 second by adding this option:
local-ttl=1

and I no longer experience this problem. I hope this information can help someone.


never mind. my MBP slept overnight, and the problem is occuring again. urgh! i should have never upgraded to Snow Leopard.
 
Joined
Dec 10, 2009
Messages
1
Reaction score
0
Points
1
This was extremely frustrating for me as well. I have two Macs in the house, a Mini and MacBook. The Mini had no problems, but the MacBook I was about ready to toss out the window. I was able to fix it just a few days ago (waited to post just to make sure that it was indeed fixed).

My Setup:
My primary DNS is running BIND on a Fedora 11 box, and I'd previously had my internet router as a secondary DNS. Both being pushed out via DHCP from that same Fedora 11 box.

On a whim I removed the internet router as a secondary DNS, so that I only had my BIND DNS from the Fedora 11 box being pushed out via DHCP. That seems to have done the trick.

I don't know the ultimate root cause, or if this solution may work for anyone else, but figured I'd pass it along for anyone else that landed here.

Good luck!
 
Joined
Dec 15, 2009
Messages
1
Reaction score
0
Points
1
Hi guys,

I'm having the same problems here on my 10.6.2 white Macbook, DNS stops working for my Airport card every now and then:
- it only happens for the Airport card (not the wired network card) => it's not a networking problem per se
- it happens shortly after waking, but can come back after "fixing" it at any time
- Disabling and reenabling the wireless card does help solving it (not permanently though)
- it happens when I use my router as DNS server as well as when I manually enter my ISP's, the OpenDNS or Google's DNS servers => it's not a problem with my router/home network
- connecting to a server based on the IP works like a charm => seems to be limited to DNS
- using dig (and the like) returns no result (timeout) => ***?
- no other computer (Linux/Windows/iPhone) are affected

I thought about reinstalling SL, but then again I get the feeling that it isn't some sort of misconfiguration, but might be a bigger problem as so many of you guys are affected :Grimmace:

Hope there's a fix for that soon!
Holger
 
Joined
Dec 16, 2010
Messages
1
Reaction score
0
Points
1
Hi guys,

I'm having the same problems here on my 10.6.2 white Macbook, DNS stops working for my Airport card every now and then:
- it only happens for the Airport card (not the wired network card) => it's not a networking problem per se
- it happens shortly after waking, but can come back after "fixing" it at any time
- Disabling and reenabling the wireless card does help solving it (not permanently though)
- it happens when I use my router as DNS server as well as when I manually enter my ISP's, the OpenDNS or Google's DNS servers => it's not a problem with my router/home network
- connecting to a server based on the IP works like a charm => seems to be limited to DNS
- using dig (and the like) returns no result (timeout) => ***?
- no other computer (Linux/Windows/iPhone) are affected

I thought about reinstalling SL, but then again I get the feeling that it isn't some sort of misconfiguration, but might be a bigger problem as so many of you guys are affected :Grimmace:

Hope there's a fix for that soon!
Holger

Have you ever got fix to this problem, my wifes mac mini is exactly the same. It looses name resolution also. I can ping things by IP and stuff but no DNS lookups work. If I turn off the airport and then turn it back on it fixes the problem, but its only temporary.
 
Joined
Jan 12, 2011
Messages
1
Reaction score
0
Points
1
Possible fix for DNS isses in Snow Leopard

Hi folks,

I recently switched to a Mac running 10.6.latest as my primary machine and ran into this exact problem. I have a LAN-based DNS server to provide addresses for the other machines on the internal network and two DNS servers provided by my ISP. Intermittently, Firefox would fail to resolve the name of an internal server.

After some searching, I found this page that suggests Apple changed the way DNS servers are queried in Snow Leopard (item #2): Apple - Support - Discussions - Changes in DNS resolution in Mac OS X ...

I found this article and made the suggested changes: OS X 10.6.3 and DNS server priority changes | MacFixIt - CNET Reviews

I hope this helps someone else get Snow Leopard to honor DNS server ordering instead of randomizing them.

Cheers,
Greg
 
Joined
Mar 8, 2012
Messages
1
Reaction score
0
Points
1
Fixed it! Good tip.

I had the same problem this morning and killing the mDNSResponders fixed it. Thanks for the tip!
 

Shop Amazon


Shop for your Apple, Mac, iPhone and other computer products on Amazon.
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.
Top