While adding rDNS file in cpanel server I was getting below mentioned error

Sorry, the domain xx.xx.104.in-addr.arpa is owned by another user (nobody)

I have found that at one point in the past this domain was present on this server.

I have removed remnants of the domain from /var/cpanel/users/system and removed references to it from /etc/userdomains and /etc/remotedomains.

I then rebuilt the various caches:

====
/scripts/updateuserdatacache
/scripts/updateuserdomains
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I am now able to add zone file without any issues