Changing the DNS servers of Public Cloud instances

Find out how to change the default DNS servers on a Public Cloud instance

Objective

The default DNS server configured on instances you create will be the OVHcloud server (213.186.33.99 for example). You can add a secondary server or replace this configuration with your own. However, the DNS servers are configured automatically by a DHCP server and you will not be able to change the DNS configuration by editing the resolv.conf file.

This guide explains how to change the DHCP configuration of an instance in order to change the DNS servers.

Warning

OVHcloud is providing you with services for which you are responsible, with regard to their configuration and management. You are therefore responsible for ensuring they function correctly.

This guide is designed to assist you in common tasks as much as possible. Nevertheless, we recommend that you contact a specialist service provider if you have difficulties or doubts concerning the administration, usage or implementation of services on a server.

Requirements

A Public Cloud instance in your OVHcloud account
Administrative access to the instance via SSH or RDP
Basic networking and administration knowledge

OVHcloud Control Panel Access

Direct link:
Navigation path: Public Cloud > Select your project

Instructions

Debian / Ubuntu

CentOS / Fedora

Windows

Using a text editor of your choice, edit the file /etc/dhcp/dhclient.conf to configure the DNS servers you want.

Replace IP1 and IP2 with the IP addresses of your DNS servers, then use the directive that fits your needs:

To replace the server configured by default:

supersede domain-name-servers IP1, IP2;

To prefer your DNS servers over the default one:

prepend domain-name-servers IP1, IP2;

To use your DNS servers only if the default one is unavailable:

append domain-name-servers IP1, IP2;

Save the file, then check that the configuration has been applied properly:

cat /etc/resolv.conf

domain openstacklocal
search openstacklocal
nameserver IP1
nameserver IP2

Check the current configuration with the command nmcli:

nmcli

eth0: connected to System eth0
        "Red Hat Virtio"
        ethernet (virtio_net), FA:16:3E:B6:FB:89, hw, mtu 1500
        ip4 default
        inet4 51.77.205.51/32
        route4 0.0.0.0/0
        route4 51.77.205.51/32
        route4 51.77.204.1/32
        inet6 fe80::f816:3eff:feb6:fb89/64
        route6 ff00::/8
        route6 fe80::/64

lo: non-managed
        "lo"
        loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536

DNS configuration:
        servers: 127.0.0.1 213.186.33.99
        interface: eth0

Retrieve the name of your public interface:

nmcli connection show

NAME         UUID                                  TYPE      DEVICE
System eth0  5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03  ethernet  eth0

Disable automatic DNS modification and add your DNS servers (replace System eth0 with the actual value, and IP1/IP2 with your IP addresses):

nmcli con mod "System eth0" ipv4.ignore-auto-dns yes
nmcli con mod "System eth0" ipv4.dns "IP1 IP2"

Apply the configuration:

nmcli con down "System eth0" && nmcli con up "System eth0"

Check that the configuration has been properly applied:

nmcli | grep -E 'DNS|server|interface'

DNS configuration:
        servers: IP1 IP2
        interface: eth0

Connect to the instance via remote desktop session or with the VNC console. Refer to our guide on Connecting to a Public Cloud instance if necessary.

Open the Network settings.

Go to your public network adapter's IPv4 configuration via the control panel.

Add the servers you want to use in the Advanced settings.

Info

In PowerShell, you can use the command nslookup to check which DNS server is used by default.

Go further

First steps with Public Cloud instances

Changing the hostname of a Public Cloud instance

Join our community of users.

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