[Q] DNS(bind) ER model

Anyone aware of an ER model for holding name server records?

Working on the zone file data and I am getting close but keep running
into the differences between MX records (with a priority) and the others
that can hold either a domain/sub-domain/host name or an IP address
depending on whether is an A, TXT, PTR, etc. or a CNAME.

Much of the database will be populated and changed automagically so the
controller for the application will do the right thing but humans will
get involved every so often. I hope I can get the database to make the
right thing easy and the wrong thing "impossible" for them.

Any suggestions?

Rod
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