Q: why do OS/X apps fail when DNS is working fine?
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Sep 4, 2013 11:26 AMby Baby Boomer (USofA),When posting in Apple Communties/Forums/Message Boards.......It would help us to know which computer model you have, which OS & version you're using, how much RAM, etc. You can have this info displayed on the bottom of every post by completing your system profile and filling in the information asked for.
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Sep 5, 2013 8:44 AMby random42,The critical detail is that "ping some.host" hangs, while "ping its.IP" works fine as do DNS lookups of "some.host". The value of "some.host" doesn't matter.
The browser (makes no difference which one, but usually chrome) "stops working" (as in can no longer load pages - claiming servers are down etc) is just a clue that once again hostname lookups are not working.
What I'd really like to know is just what thing OS/X apps use for name lookups because obviously they don't use DNS directly, and that other thing is the one that likely needs a kick in the head from time to time.
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Sep 5, 2013 10:53 AMby BDAqua,How are you connecting & what are your DNS settings?
What DNS settings are in your Router?
Make a New Location, Using network locations in Mac OS X ...
http://support.apple.com/kb/HT2712
10.5, 10.6, 10.7 & 10.8…
System Preferences>Network, top of window>Locations>Edit Locations, little plus icon, give it a name.
10.5.x/10.6.x/10.7.x/10.8.x instructions...
System Preferences>Network, click on the little gear at the bottom next to the + & - icons, (unlock lock first if locked), choose Set Service Order.
The interface that connects to the Internet should be dragged to the top of the list.
If using Wifi/Airport...
Instead of joining your Network from the list, click the WiFi icon at the top, and click join other network. Fill in everything as needed.
For 10.5/10.6/10.7/10.8, System Preferences>Network, unlock the lock if need be, highlight the Interface you use to connect to Internet, click on the advanced button, click on the DNS tab, click on the little plus icon, then add these numbers...
208.67.222.222
208.67.220.220
(There may be better or faster DNS numbers in your area, but these should be a good test).
Click OK.
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Sep 5, 2013 11:14 AMby MrHoffman,As a guess, there's a bad DNS server in your ISP's DNS server pool.
8.8.8.8 and 8.8.4.4 are Google's open-access DNS servers. Easier to remember than the ones BDAqua suggested, but the same request to try a different pool of DNS servers.
FWIW, dig bypasses local DNS caching and goes to the default or the specified DNS servers, where ping uses local DNS caches
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Sep 5, 2013 2:05 PMby random42,I'm sitting on a segment of a corporate network, DNS isn't the problem - it still works.
Connectivity isn't the problem - it still works.
The issue is that OS/X obviously uses something other than DNS to do name lookups - which doesn't always work, but no one seems to have a clue what that is.
HUP'ing the usual suspects (mDNSResonder) and clearing caches makes no difference.
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Sep 5, 2013 2:17 PMby MrHoffman,Since this is a web browser that's involved and other services are apparently working, some other HTTP- or HTTPS-level component may well be in play here, such as a network filter, network security monitor, a firewall, or a network proxy server. You'll have to check the local settings, and see where the "stops working" is arising.
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Sep 5, 2013 4:47 PMby etresoft,random42 wrote:
I'm sitting on a segment of a corporate network, DNS isn't the problem - it still works.
Connectivity isn't the problem - it still works.
The issue is that OS/X obviously uses something other than DNS to do name lookups - which doesn't always work, but no one seems to have a clue what that is.
HUP'ing the usual suspects (mDNSResonder) and clearing caches makes no difference.
Obviously DNS is the problem or else you wouldn't have posted anything. What happens when you use a 3rd party DNS like OpenDNS or Google? Does the problem go away? We are all using OS X too and not having any problems. Your problems must come from whatever is different about your network. Corporate networks often do funky things to network setttings and are rarely tested on anything but Windows. You seem pretty handy with UNIX, so use the scutil command to poke around at what your dynamic network configuration actually looks like.
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Sep 5, 2013 5:09 PMby g_wolfman,If a WINS server is pushing multiple search domains in the DHCP setup, OS X will not always pick them up and this can cause problems.
scutil --dns will show you the current setup of the resolver cache, including the resolvers established for DHCP promulgated search domains.
From Snow Leopard (or maybe Lion) onwards, all "native" DNS queries are made through the mDNSResponder Daemon, in much the same way that launchd acts as a "super-listener" for all active server ports coming inbound.
If HUPing mDNSResponder is having no effect, then the daemon is working correctly, and it must be a problem in the configuration - again, something most likely caused by the DHCP setup when joining your network.
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Sep 6, 2013 1:59 PMby random42,Thanks scutil --dns may prove useful next time thins happens.
Right now the results look sane.
HUP'ing mDNSResponder though doesn't help, and as previously noted dns lookups from this host using tools like dig and host work fine while apps like ping (and browsers and everything else) cannot resolve names.
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Mar 24, 2014 2:45 AMby rAWTAZ,random42: Have you found out any additional details on this matter?
I've had the same thing happen a number of times, same symptoms although the problem is noticed when using Mail. I agree with what you say, it's like OS X's internal DNS infrastructure "hangs", even though DNS *is* fine - DNS lookups from the machine, using `host` etc, works fine. It's something inside OS X that stops working, and I haven't found a way to kick it live again either, nothing short of a reboot helps AFAIK at this point in time.
It's been happening on both 10.8 and 10.9 for me. It might have been on 10.6 as well, I don't remember.
EDIT: I'm gonna try the solution proposed in https://apple.stackexchange.com/questions/26616/dns-not-resolving-on-mac-os next time it happens.
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Sep 21, 2014 10:52 PMby applcola,i have been experiencing something similar to the issues being observed in this post.
I have done more troubleshooting and here are the details of our situation
User - Macbook pro 13" 10.9.4. Mavericks
Enterprise wireless - Aruba Wireless
[symptom] User cant print -
[reason] he cant print because OSX cant properly ask for the DNS to IP query.
[sympton] User believes DNS Server is having issues
[reason] DNS does not answer because when we saw his problem... and ran TCPdump in the back... we can clearly see the OS does not append the suffix
[sympton] User shuts down wireless and restarts it... issue goes away
[reason] Stack gets restarted and whatever process was stale... it is back up and running post process restarted.
Observation 1
This issue appears to surface randomly when the user laptop goes to sleep... not always
Observation 2
User is always wireless connecting to the network
Observation 3
User tries to print to a network printer... different subnet than wireless
Hypothesis 1
Issue lies due to conflict between DNS and Bonjour. Something gets corrupted in DNS and Bonjour takes over. however Bonjour does not work outside the subnet it is in as it uses Multicast.
DNS goes out since the workstation goes to sleep losing its ip address.
Corporate DNS uses LDAP authentication
Bonjour is zero configuration and could stay running if configured.
therefore IP queries to device work. ip queries to fully qualified name work. making the OSX query the name by common name does not work.
not sure how close I am to solving my issue
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