I have a pi hole in my network and I set it as my primary DNS server, and my router (a Mikrotik) as secondary. DHCP sets the DNS servers as pihole, mikrotik in this exact order and I want to keep it that way. I know systemd-resolved uses some algorithm to set the fastest dns as current server, but I don’t want/need that. Is there some way to do configure it to just let it be?

I’m running Fedora 40.

  • atzanteol@sh.itjust.worksEnglish
    2·
    3 months ago

    You can’t. Well, you shouldn’t rely on queries going out in any particular order. All of your DNS servers should behave the same way as clients may fail from the first one to a secondary.

    Why do you care which one is being used? What are you trying to do?

  • nelsnelson [comrade/them, love/loves]@hexbear.netEnglish
    1·
    3 months ago

    Via ChatGPT 4 (accuracy unverified):

    Yes, you can configure systemd-resolved to use the DNS servers in the order provided without dynamically switching based on speed. Here’s how you can do it:

    1. Edit the resolved configuration file:

      Open the resolved.conf file in a text editor:

      sudo nano /etc/systemd/resolved.conf

    2. Modify or add the following line:

      DNS=`IP_of_pihole` `IP_of_mikrotik`
DNSStubListener=no
FallbackDNS=

      Replace IP_of_pihole and IP_of_mikrotik with your actual DNS IP addresses. This tells systemd-resolved to only use the DNS servers in the order you’ve specified.

    3. Prevent automatic DNS changes by network manager:

      If you’re using NetworkManager, create a drop-in configuration to prevent it from overriding DNS settings:

      sudo mkdir -p /etc/NetworkManager/conf.d/
sudo nano /etc/NetworkManager/conf.d/dns.conf

      Add the following content:

      [main]
dns=none

    4. Restart services:

      After making these changes, restart systemd-resolved and NetworkManager:

      sudo systemctl restart systemd-resolved
sudo systemctl restart NetworkManager

    This should ensure that your system uses the DNS servers in the order provided without any automatic switching.