In the radv protocol in bird, there is a possibility to pass DNS servers to the clients. This requires a working recursive DNS server. If you only want to resolve CRXN domains, you can use a DNS server from Additional/DNS. If you also want to resolve Clearnet domains, it is recommended to use your own DNS resolver (recursive or forward) like Coredns or Unbound.

With the following option, you can specify a DNS server:

rdnss fd92:58b6:2b2::5353;

The following option allows you to specify multiple DNS servers:

rdnss {
    ns fd92:58b6:2b2::5353;
    ns fd92:58b6:2b2::5354;

If you also have a CRXN domain, you can also tell the clients a search domain:

dnssl "home.example.crxn";
dnssl {
    domain "home.example.crxn";
    domain "lab.home.example.crxn";