The 101 of domain and certificate contacts
These settings make up the WHOIS record data for a domain.
The owner is the legal entity owning the domain. For a company, the company itself with an ORG type of contact
The end customer's administrative person or domain team (size matters ;)
An email address is needed, this person should be reachable for both other IT people or legal inquiries
The IT person for technical matters, usually at the ISP running the nameserver
The IT person for DNS zone related questions only, at the ISP running the nameserver.
The contact should match with the Admin-C, i.e. firstname.lastname@example.org
The legal entity should match with the Owner-C, i.e. my pet stop shop, inc.