SSH into Mythos, vim /etc/knot/zones/vern.cc.zone
Here i have made sections for each machine and a last one for mail.
Add A record (ipv4) in the correct section and AAAA (ipv6) if applicable
Copy existing records that we already have in the file instead of creating a new one, dns stuff is a bit finicky.
It can be written as
iceberg.vern.cc.\tA\t173.255.236.85
or
iceberg\tA\t173.255.236.85
same for AAAA/TXT
(Needless to say, replace \t with an actual <tab>)