Reverse DNS or rDNS is easily mixed with DNS NS, A, CNAME, TXT ... records, although the principle is the same the rules are a bit different and to save some writing a short and effective explanation can be found here.
Reverse DNS is confusing but not too difficult to understand.
When troubleshooting rDNS, first we need to find out the authoritative name servers to the IP address we are having issues with and the recommended tool is this one provided by RIPE itself.
Let's query the name servers in charge of the PTR records for the IP address 220.127.116.11 which belongs to one of my servers on the data centre.
The result pointed us to
NS2.4D-DC.COM as the name servers in charge of 18.104.22.168 PTR records.
We can now log in to the servers and check the entries for the reverse zone under the domain
167.160.185.in-addr.arpa for any errors and if we do not have direct access to the name servers we will have to get in touch with the support team of whoever manages these name servers.