In my DNS administration software I have a option to create a new DNS zone and option to add records to existing DNS zone that I use for my first domain.
I would like to add next doman in DNS. Should I put it into existing zone or create new one? I'm a beginner in DNS configuration so a little explanation here would be great.
You should have one zone per domain, so everything for domain1.tld would go in domain1.tld.zone and entries for domain2.tld would go in domain2.tld.zone (or wherever your specific software stores zones).
What seems like the exception is reverse DNS zones files, but they actually function the same way, just think of the domain being 192.168.1. So anything with a 192.168.1.x IP would go in 1.168.192.in-addr.arpa.zone and it could contain
PTR
s in domain1.tld & domain2.tld.