I do have a Debian server running a BIND9 DNS server. In my zone file, I have several hosts that are equally reachable via IPv4 and IPv6 and they do have their respective A or AAAA records.
Now I wanted to add an IPv6-only host to my zone, this is a computer running in my home network. This computer has an IPv6 address that is reachable from the internet / my DNS server machine (I can ping6 the address directly). However, it does not have an IPv4 address (because it is NATted behind my router etc.).
I thought that it would not matter and I can simply add a AAAA record for this host with the IPv6 address and be able to ping it.
The thing is that I can only ping this machine when using ping6, the standard ping command gives me unknown host. This is somehwat understandable, but I wonder why the normal ping has no problems with pinging one of the hosts that have an IPv4 and and IPv6 record - in this case, the normal ping resolves to the IPv6 address.
Is there an explanation for that and what can I do to change this behaviour?
Host has A + AAAA record: ping resolves to IPv6 address, ping6 resolves IPv6 address
Host has AAAA record only: ping does not resolve IPv6 address, ping6 resolves IPv6 address