man hostname, being cited from its end to beginning
/etc/hostname Historically this file was supposed to only contain the hostname and not the full canonical
FQDN. Nowadays most software is able to cope with a full FQDN here. This file is read at boot time by the
system initialization scripts to set the hostname.
/etc/hosts Usually, this is where one sets the domain name by aliasing the host name to the FQDN.
The FQDN (Fully Qualified Domain Name) of the system is the name that the resolver(3) returns for the host
name, such as, ursula.example.com. It is usually the hostname followed by the DNS domain name (the part
after the first dot). You can check the FQDN using hostname --fqdn or the domain name using dnsdomainname.
You cannot change the FQDN with hostname or dnsdomainname.
The recommended method of setting the FQDN is to make the hostname be an alias for the fully qualified name
using /etc/hosts, DNS, or NIS. For example, if the hostname was "ursula", one might have a line in
/etc/hosts which reads
127.0.1.1 ursula.example.com ursula
Technically: The FQDN is the name getaddrinfo(3) returns for the host name returned by gethostname(2). The
DNS domain name is the part after the first dot.
Therefore it depends on the configuration of the resolver (usually in /etc/host.conf) how you can change
it. Usually the hosts file is parsed before DNS or NIS, so it is most common to change the FQDN in
If a machine has multiple network interfaces/addresses or is used in a mobile environment, then it may
either have multiple FQDNs/domain names or none at all. Therefore avoid using hostname --fqdn, hostname
--domain and dnsdomainname. hostname --ip-address is subject to the same limitations so it should be
avoided as well.
I'd say it does describe the whole thing thoroughly.