This free online tool from SolveDNS allows you to lookup the reverse DNS entries for an IP or an IPv6 address. You can also enter a domain name or a host name and we will search for its A and AAAA records as well as its MX Record IP addresses and then convert all those IPs to their reverse DNS host names. We will also output the location of the IP addresses
It is important that you have reverse DNS (PTR Record) entries for all your IP addresses, especially your MX record IPs. Mail servers without reverse DNS entries might cause problems while sending email through some recepient email servers.