Currently Being ModeratedNov 14, 2011 1:08 PM (in response to X423424X)
It's nice of you to reply. But the existing DNS server (which by the way is on our LAN) is giving the proper answers.
This only happens with *one* computer on the network, and then only sometimes. But when the computer is exhibiting this problem, dig and nslookup both resolve IP addresses correctly - but apps like Safari and Mail seem unable to use this information.
The only way I have found of sorting this is to restart the client computer, at which point it works fine.
Logging out and back in as a different user has no effect.
Currently Being ModeratedNov 28, 2011 9:40 AM (in response to James Knight3)
can anyone help? this happens every time we bring this laptop on to our network. I've deleted the ethernet interface and added it again, tried with different users, but nothing works apart from a restart.
The DNS resolves IP addresses perfectly, and the IP addresses can be pinged but no URL can be pinged or used in any way.
Currently Being ModeratedNov 28, 2011 10:29 AM (in response to James Knight3)
You can override normal lookups by setting a hostname in /etc/hosts to give it a different IP address.
Safari (and just about every other application) will use the system resolver to resolve the hostname, and that first checks /etc/hosts to see if an entry exists. If it does, it uses that address rather than whatever DNS would say.
However, dig specifically queries the name server, so will return whatever DNS says, completely ignoring /etc/hosts and any caches.
Currently Being ModeratedNov 28, 2011 11:44 AM (in response to Camelot)
Thanks Camelot - that would be fine if this was one IP address I was having problems with. But that's not it. No URLs at all can be accessed - whether hosted locally or on the internet. Both dig and nslookup resolve IP addresses correctly but the URLs do not work.
From your post, it sounds as thought the system resolver may be at the root of the problem. But I have no idea how I would go about unclogging it?
Currently Being ModeratedMar 7, 2012 5:27 AM (in response to James Knight3)
does anyone have any more ideas on this? The laptop only appears to have this problem on our LAN - it's fine at another office or at home. But no other computers exhibit this behaviour at all. Every time the user plugs on to our LAN, it works at first and then after a period it suddenly gives up resolving domain names. Help please!
Currently Being ModeratedMar 7, 2012 5:38 AM (in response to James Knight3)
James Knight3 wrote:
does anyone have any more ideas on this?
Create a new user account on the same machine and test it. At least it will give you an idea on where to look for the trouble. If Safari and Mail don't display the same issue in the new user account, then the problem must be somewhere in the other account's Home folder.