###
dns
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:date: 2021-09-16 00:00
:modified: 2021-09-16 00:00
:tags: domainname
:category: documentation
:slug: dns
:authors: Ms.Leave-A-Mix
:summary: DNS Configuration tips


-------
LibVirt
-------

Libvirt uses dnsmasq as a DHCP server and a DNS server for the libvirt-network daemon, it is
configured by the network's XML, you can edit it live (without having to restart
it) or via an XML file. I use the live mode because I prefer to keep the network
up when adding a new virtual machine in the configuration.

Tip : Try your dns server with the nslookup command.


.. code-block:: xml

   -- xml mode
   <network>
      ...
      <dns>
         <forwarder addr='dns.ip.address'/>
         <host ip='host.ip.address'>
         <hostname>vmhostname</hostname>
         </host>
      </dns>
      ...
   </network>

   -- live mode
   virsh net-update default add dns-host \
     "<host ip='host.ip.address'> \
        <hostname>vmhostname</hostname> \
      </host>" \
      --live --config



This DNS server is used by default on virtual machines that use default
configuration with DHCP.

You may want to use a dedicated server to handle the DNS requests, in this case
you just have to configure your operating system as described below with the
correct IP (here I use 192.168.42.1 which is the libvirt/dnsmasq server).




------
Debian
------

Bullseye
--------

On Debian Bullseye, the way to configure your DNS addresses depends on how your
network is configured. With a fresh install, you can simply edit the dhclient
configuration file and add the following option :


.. code-block:: dhcp.conf

   # If you want to keep the DNS address provided by the DHCP server
   prepend domain-name-servers 192.168.42.1;

   # If you want to use only the local DNS server
   supersede domain-name-servers 192.168.42.1;


Restart the network and normally, resolv.conf will contain the following lines :

.. code-block:: resolv.conf

   nameserver 192.168.42.1

   # If you choosed to "prepend", the DHCP provided name server is used
   nameserver 213.186.33.99