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Change Hostname (Rename a Host) - Linux

Best-practices for naming hosts

(from Citrix: Install Linux Virtual Delivery Agent for Ubuntu
and He, Peng: Change the Username and Hostname on Ubuntu)

Table of Contents

Prerequisites

  • It is best the network is connected and configured correctly before proceeding
  • If you are using a Ubuntu 18.04 Live Server, make the following change in the /etc/cloud/cloud.cfg
    configuration file before setting the host name:
    preserve_hostname: true

Choose a Valid Hostname

  • Use a-z, A-Z, 0-9, and hyphen (-) characters only
  • Avoid underscores (_), spaces, and other symbols
  • Do not start a host-name with a number
  • Do not end a host-name with a hyphen

Change the Hostname

To ensure that the host-name of the machine is reported correctly,
change the /etc/hostname file to contain only the host-name of the machine,
i.e.: NOT the FQDN (Fully-Qualified Domain Name).

sudo nano /etc/hostname

Assign a Loopback Address to the Hostname

To ensure that the DNS domain name and FQDN of the machine are reported back correctly,
change the following line of the /etc/hosts file to include the FQDN and host-name as
the first two entries:

127.0.0.1 hostname-fqdn hostname localhost

For example:

127.0.0.1 my-server.example.com my-server localhost

Remove any other references to hostname-fqdn or hostname from other entries in the file.

Reboot

Reboot the server so the changes will take effect,
for example:

sudo reboot

Check the host name

Verify that the host-name is set correctly

run:

hostname

This command should return only the host-name of the machine and not its FQDN.

Verify that the FQDN is set correctly

run:

hostname -f

This command returns the FQDN of the machine.

Optional - Disable multicast DNS

The default settings have multicast DNS (mDNS) enabled,
which can lead to inconsistent name resolution results.

To disable mDNS, edit /etc/nsswitch.conf and change the line containing:

hosts: files mdns_minimal [NOTFOUND=return] dns

To:

hosts: files dns