centos – How is the reverse DNS being served when I don’t have a PTR record

I’m running a HostGator dedicated server with CentOS v7.9.2009. I do not have any PTR records. I verified that in the DNS Zone Manager and the file: /var/named/proscan.org.db. When I entered ‘nslookup 162.241.136.65’ I received back ‘65.136.241.162.in-addr.arpa name = proscan.org.’

My question is: Where is the PTR record or (rDNS) coming from? Is the PTR record automatically generated from the A record? What I’m trying to do is make the PTR record show ‘mail.proscan.org‘ and not ‘proscan.org‘. I’ve been playing with the PTR records in the DNS Zone Manager all day but it seems they are overridden.

I tried adding a PTR record in the DNS Zone Manager ‘mail.proscan.org PTR 65.136.241.162.in-addr.arpa’ but the ‘nslookup 162.241.136.65’ still shows ‘proscan.org‘ and not ‘mail.proscan.org‘