Getting reverse DNS going is done by finding the PTR records in use by a DNS server. These PTR records will be managed by the company that is in control of the IP address which was assigned to you. It could be your hosting company or if the host has delegated reverse DNS for your group of IP addresses to you then you’ll be in control of reverse DNS. PTR records will usually contain the IP address backwards, which is followed by an entry that reads in-addr.arpa.
Please note that PTR records for reverse DNS can be configured for both IPv4 and for IPv6. However, where reverse DNS is set for an IPv6 address it must contain the whole IP in the PTR record and each number or letter is separate by a period. When you make a reverse DNS lookup for an IPv6 address you’ll see all of the zeros too, these are normally omitted when quoting an IPv6 address.