rDNS Record Verification
Assuming you have already created your rDNS record, added it to your DNS, and want to check your rDNS configuration. The rDNS record is stored in DNS as PTR and you can manually check the rDNS record for an IP address by using nslookup or dig as follows
1. In the terminal type
nslookup -type=PTR yourIP
dig -x yourIP
Replace yourIP with your IP address,
2. If an rDNS record exists, the result would contain your domain name.
To test your rDNS, you can also check if the DNS entry for your rDNS is correct by entering your IP address into https://mxtoolbox.com/ReverseLook up.aspx. If you set your DNS entry correctly it will show you your domain meaning your rDNS passed the test.