Adding a DNS Server

Photon OS uses systemd-resolved to resolve domain names, IP addresses, and network names for local applications. The systemd-resolved daemon automatically creates and maintains the /etc/resolv.conf file, into which systemd-resolved places the IP address of the DNS server. You must not modify the /etc/resolv.conf file.

Note: If you want to implement a local resolver like bind instead of systemd-resolved, stop the systemd-resolved service and disable it.

If you open the default /etc/resolv.conf file after you deploy Photon OS, it looks like this:

root@photon-rc [ ~ ]# cat /etc/resolv.conf
# This file is managed by systemd-resolved(8). Do not edit.
#
# Third party programs must not access this file directly, but
# only through the symlink at /etc/resolv.conf. To manage
# resolv.conf(5) in a different way, replace the symlink by a
# static file or a different symlink.

nameserver 198.51.100.2

To add a DNS server, insert a DNS key into the Network section of the static network configuration file, for example, /etc/systemd/network/10-eth0-static.network and set it to the IP address of your DNS server:

[Match]
Name=e*

[Network]
Address=198.51.0.2/24
Gateway=198.51.0.1
DNS=198.51.0.1

Note: To apply the changes made to /etc/systemd/network/*.network files, perform the following:

• Restart systemd-networkd and systemd-resolved services by running the following commands:
  • systemctl restart systemd-networkd
  • systemctl restart systemd-resolved

If your machine is working with DHCP, you can add a DNS server by modifying the /etc/systemd/resolved.conf--a method.

For more information, see https://www.freedesktop.org/software/systemd/man/resolved.conf.html.

You can optionally activate the local DNS stub resolver of systemd-resolved by adding dns and resolve to the /etc/nsswitch.conf file. To do so, make a backup copy of the /etc/nsswitch.conf file and then execute the following command as root:

sed -i 's/^hosts.*$/hosts: files resolve dns/' /etc/nsswitch.conf

For more information about the systemd-resolved service, see https://www.freedesktop.org/software/systemd/man/systemd-resolved.service.html.