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Re: Should hostname always be lower case?



On 12/05/2014 19:00, Nemeth Gyorgy wrote:
2014-05-12 16:03 keltezéssel, Ron Leach írta:

May I ask whether the 'case' of the hostname is important, in the sense
that use of any upper-case characters may disrupt name resolvers?

We have a server running wheezy, and we named it D7Server (not
d7server).  Could this matter to any resolver attempting to look up
D7Server?  (It might matter, for example, if standards allow resolvers,
generally, to assume that names to be resolved will be lower case.)

If you consider DNS resolving only then you can use any case and upper
and lowercase will be the same.

But if you name your host with upper-case characters, you will face some
trouble on your local host. So you better not do it.




Ah. Trouble on the local host is one of the problems we have. The other is with a DNS resolver on the LAN (that resolver is not running Debian). Name resolution is an issue in itself, and I was going to post separately with those details, but perhaps I could post here, to follow your remark.

Our difficulty is in stopping name resolution requests for hosts, that are local to our LAN, from going to a DNS resolver. The machine I'm trying to setup is running wheezy. Its name is D7Server, and the domain in /etc/resolv.conf is 'inet'. The same issue seems to occur on some servers running earlier versions, as well.

I've read man hosts, resolv.conf, and nsswitch.conf; I've also had a look at
http://www.debian.org/doc/manuals/debian-reference/ch05.en.html#_the_hostname_resolution
(I'm assuming that's an official site).

On the Wheezy machine, /etc/nsswitch.conf contains

hosts:	files mdns4_minimal [NOTFOUND=return] dns mdns4

From my reading, since 'files' is listed first, /etc/hosts should be checked for name resolution first, with external requests to a dns resolver *only* if the host name is not found in hosts file.

But the behaviour I am seeing is that the box is asking for resolution (of its own hostname, actually) from an external resolver. (That DNS resolution request fails, anyway, because there is no record for its hostname in the DNS tree.)

/etc/hosts, on D7Server, contains a record for D7Server:
192.168.3.31<tab>D7Server<tab>d7server<tab>D7Server.inet<tab>d7server.inet

Despite the entry in hosts file, D7Server keeps asking the DNS resolver to lookup D7Server (the request is logged on the DNS resolver machine), instead of reading it from its hosts file.

Do I need to do something more to enable names to be looked up in /etc/hosts?

regards, Ron


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