Question

FQDN set up on Ubuntu 20

Number one, what is a Fully Qualified Domain Name? Secondly, how do I check to see if it is set up (what command line do I enter)? Thirdly, if it is not set up, then, how do I go about setting it up?


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Hi @aecsp2000,

FQDN or Fully Qualified Domain Name is your Droplet’s full hostname. Usually, you are able to ping your Droplet with that FQDN and it’s used for PTR records.

To set one, you need to enter your Droplet via SSH and:

Change the hostname using hostnamectl

The first step once you have entered the droplet would be to use the hostnamectl command. Let’s say we want to name our droplet ‘ExampleName’. To do so, we need to execute the command like so

sudo hostnamectl set-hostname ExampleName

The hostnamectl command does not produce output. On success, 0 is returned, a non-zero failure code otherwise.

Update the /etc/hosts file

Next on our list would be to update the hosts file located in the etc folder. You can use any editor you want from nano, vi, vim.

sudo nano /etc/hosts

In there you’ll see something similar to

# Your system has configured 'manage_etc_hosts' as True.
# As a result, if you wish for changes to this file to persist
# then you will need to either
# a.) make changes to the master file in /etc/cloud/templates/hosts.debian.tmpl
# b.) change or remove the value of 'manage_etc_hosts' in
#     /etc/cloud/cloud.cfg or cloud-config from user-data
#
127.0.1.1 PreviousNameHere
127.0.0.1 localhost

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

Change the line which says the following

127.0.1.1 PreviousNameHere

to be

127.0.1.1 ExampleName

Save the file and exit.

That should be it.

Changing PTR

DigitalOcean automatically configures the reverse dns entry (PTR) on their end. It will be the hostname you choose when you set up your dropplet. You can change/check this in the control panel by selecting your dropplet, then settings, then rename. As it says, changing the name there will update the PTR but not the hostname of the system, that is something you will need to do, instructions for that vary depending on the system you have installed.

Hope this helps! Let me know if you have any questions.