El Capitan server DNS not resolving host

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axel marc Author

Level 1

8 points

El Capitan server DNS not resolving host

The server does not seem to resolve the 'root' host

I upgraded from a Snow leopard server environment to El Capitan's server 5.0.15.

The server is running on a basic mac mini that is now about 2 weeks old.

Followed the DNS settings instructions. Hosts like www.example.com are working perfectly fine.

However the server does not resolve example.com. On Snow Leopard server I used to create A records for hosts like example.com as well as www.example.com, but this seem to be not possible anymore.

Any idea?

Thanks XL

Mac mini, OS X El Capitan (10.11.2), Server 5.0.15

Posted on Dec 22, 2015 4:04 PM

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Answer 1

axel marc Author

Level 1

8 points

Dec 22, 2015 4:10 PM in response to axel marc

to be more precise this is what I get when a ping is done:

ping: cannot resolve example.com: Unknown host

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Answer 2

Dec 22, 2015 4:45 PM in response to axel marc

That usually doesn't work right, through the GUI. Shut down the DNS server and edit the zone file.

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Answer 3

axel marc Author

Level 1

8 points

Dec 22, 2015 5:16 PM in response to MrHoffman

Thanks Mr Hoffman,

yes, I started to wonder if it was a GUI issue or a restriction. Will work on it now.

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Answer 4

axel marc Author

Level 1

8 points

Dec 22, 2015 6:18 PM in response to axel marc

it does not work.

I stopped the DNS server, made a ** copy of the file

I did nano edit the file (~/named/db.example.com), added one A record for example.com. (no www. in front) , wrote out and restarted the DNS server.

When you ping it stil can not be resolved. It just says unknown host

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Answer 5

Dec 22, 2015 7:09 PM in response to axel marc

Trailing dot after the host name; is it specified as an FQDN? Does a dig resolve the address? (I'd expect not.) In the response to the dig, check which name server responded, and make sure it's the one you expect. Having more than one name server specified in System Preferences > Network can lead to confusion here, if all of the servers are not using the same data.

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Answer 6

axel marc Author

Level 1

8 points

Dec 22, 2015 7:31 PM in response to MrHoffman

dig resolves the address indeed.

ping does not for the example.com, but does resolve if there is host name in front, such as www.example.com

FQDN: domain name always used as such, since 19 years

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Answer 7

axel marc Author

Level 1

8 points

Dec 22, 2015 11:53 PM in response to axel marc

small update

things started to improve after I changed the Perform lookups for all clients ;

doing a test now with only allowing lookup for the server itself.

Yet, in both cases the dig resolves the address example.com , ping does not. Ping however does resolve if there is host like www.example.com

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Answer 8

Dec 23, 2015 5:35 AM in response to axel marc

Is there more than one DNS server listed in the DNS server list in  > System Preferences > Network > select network > DNS?

If so, reduce that list to just the server's own IP address, flush the DNS caches with dscacheutil -flushcache and try the tests again.

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Answer 9

axel marc Author

Level 1

8 points

Dec 23, 2015 6:52 AM in response to MrHoffman

Thank you Mr. Hoffman,

DNS setting was fine and limited to only one server - thanks for pointing that out, I did not know. Another of your recommendations I did was to add with nano one A record for the domain name only, example.com i.e., no host like www or so before. After restarting the DNS server it got wiped out. did that 2x and decided to not insist.

But the case got resolved a couple hours ago after doing this:

- I switch off first the lookup from for this server only to all users. After about 30' it started to get alive again. I restricted the lookup again 1 h later (using the GUI) and the server kept working.

The server was actually perfectly fine for the first few days, but I left the lookup open to all. Looking back in the logs I changed two settings some hours before the problems started by first limiting the lookup to the server only and doing so with the GUI indeed. Another change I made was I did setup the new server as a primary next to the old primary, to assure a transition of some time. So I had two primary DNS servers (equal setup) and two secondary for a while 4 days before changing the old primary into a secondary dns server, around the same time I restricted the lookup. So what was causing the problem? I do not know.

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