How to Set the Hostname on a Linux VPS

Every Linux server ships with a generic hostname like localhost or vps-12345. That's fine for a single box, but the moment you have two servers your logs become ambiguous, your shell prompt loses meaning, and automation tools can't tell them apart. This guide sets a proper hostname — both the short name and a fully qualified version — in a way that survives reboots cleanly.

Three hostnames, not one

Modern Linux actually tracks three hostnames at once. Knowing which is which saves a lot of confusion later.

• Static — the name in /etc/hostname. Set once, persists across reboots. This is what you usually want to change.
• Pretty — a human-readable label like "Yossi's Web Server". Mostly cosmetic, shown in some GUIs.
• Transient — runtime-only value, can be set by DHCP or container orchestrators. Resets on reboot.

1See what's currently set

# All three hostnames at once
hostnamectl

# Or read individually
hostname              # short name
hostname -f           # FQDN (resolved via /etc/hosts and DNS)
cat /etc/hostname     # what survives reboot

2Change the static hostname

hostnamectl is the one-stop tool on systemd-based distros. It updates /etc/hostname, the running kernel's hostname, and the systemd machine info file in one shot.

# Replace web01 with your chosen short name
sudo hostnamectl set-hostname web01

# Optional: set a friendly "pretty" label
sudo hostnamectl set-hostname "Production Web Server" --pretty

# Verify
hostnamectl

3Wire the hostname into /etc/hosts

This is the step people forget — and then sudo complains "unable to resolve host web01" every time. Many programs (including sudo) resolve their own hostname before doing anything else, and they look at /etc/hosts first. The entry needs to match the new name exactly.

# Edit the file
sudo nano /etc/hosts

# Ensure these two lines exist (the second is the important one)
127.0.0.1   localhost
127.0.1.1   web01.example.com web01

The 127.0.1.1 line is a Debian/Ubuntu convention for the machine's own hostname. RHEL family typically uses a real interface IP there, but 127.0.1.1 works on both.

4Confirm DNS resolution works for the FQDN

# Should print the FQDN
hostname -f

# Should resolve to a real IP (the /etc/hosts entry, or a real DNS A record)
getent hosts web01.example.com

# Confirm sudo no longer complains
sudo -n echo "hostname is happy"

What about cloud-init? It may overwrite your change

On VPS images that ship with cloud-init (most Ubuntu, AlmaLinux, and Rocky images), the first boot can re-set the hostname from VPS metadata. If your hostname change is ignored after a reboot, this is the cause.

# Open the cloud-init config
sudo nano /etc/cloud/cloud.cfg

# Set these two values
preserve_hostname: true
manage_etc_hosts: false

After that change, hostnamectl set-hostname is the only thing that controls the hostname — cloud-init won't touch it.

Setting a real FQDN (the proper way)

If you own a domain and want the server reachable as web01.example.com from anywhere, you need DNS, not just /etc/hosts. /etc/hosts only affects the local machine; the wider internet doesn't see it.

1. In your DNS provider, create an A record: name web01, value — your VPS's public IP.
2. Wait a few minutes for propagation. Test from another machine: dig web01.example.com.
3. Once DNS resolves, leave /etc/hosts as the local fallback — some services prefer it.
4. If the server sends mail, also add a PTR (reverse DNS) record via your VPS provider's control panel. We provide a self-serve PTR editor in every client area.

Frequently asked questions