I am aware that the primary server listed in SOA record has to be valid for DDNS to work.
Is anyone aware of any other application that uses the SOA listed primary DNS server in one way or the other?
By a fake primary server I mean either:
Inaccessible by anything else other than secondary servers (this is called hidden primary correct? unsure).
A completely fake domain name like
dig +short soa spamhaus.org