[CentOS] Short or long hostname ?

Fri Apr 12 05:28:04 UTC 2019
Simon Matter <simon.matter at invoca.ch>

>> On 4/10/19 8:23 AM, Simon Matter via CentOS wrote:
>>>> Hi,
>>>> For the last ten years or so, I've defined the short hostname in
>>>> /etc/hostname and the FQDN in /etc/hosts. Now I wanted to double-check
>>>> this information, which eventually led me to this page:
>>>>    *
>>>> https://serverfault.com/questions/331936/setting-the-hostname-fqdn-or-short-name
>>>> Now I admit I'm even more confused than before.
>>>> Is there some reliable piece of information on this subject for CentOS
>>>> ?
>>> IMHO for those having proper DNS in place, the hostname should be set
>>> to
>>> the FQDN in whatever place it is supposed to be set. I quite feel there
>>> is
>>> something wrong if the only place where the FQDN is listed is the
>>> /etc/hosts file.
>>> I'm not very happy with how the issue was handled in Linux and the
>>> different distributions in the last decades. Not to mention the
>>> inconsistency in the relevant man pages.
>> Well, I am unhappy for about as long about /etc/hosts and how name
>> resolution "should" happen which it doesn't, namely, if
>> /etc/nsswitch.conf says
>> hosts: files dns
>> then ideally /etc/hosts should be used first, then nameservers. However
>> (and this is true both for Linux and FreeBSD), some commands never look
>> into /etc/hosts (e.g., command host), whereas some do use /etc/hosts
>> (e.g., command ping).
> Well, in case of the host command it seems clear that it doesn't look up
> /etc/hosts as it is a "DNS lookup utility", as the man page states, and
> not a general name resolution utility. I had to learn this, guess how.

It's my impression that trying to resolve a host on a Linux system (and
also other *nix like systems) is best done with the getent utility:

getent hosts <hostname>

It shows what other programs see as well.