With the help of reverse lookup, one can check the domain name associated with an IP, which in turn is identified using a record lookup. This type of valid two-way DNS mapping is done by email providers to categorize the domains as valid or invalid. This is mainly used by companies for lead identification and protecting the domain from spam and other attacks.

A reverse domain name system (DNS) lookup, or reverse IP lookup, is the opposite sequence of a DNS lookup. It's essentially a reverse IP tracker. With a standard DNS lookup online, you query the DNS server or hostname to get the IP address. But with the reverse DNS lookup command, you query the IPv4 address or IPv6 address to find the hostname. Therefore, when entering the IP address into the reverse lookup tool, it tests PTR records, allowing users can locate the domain name associated with the corresponding IP.

A reverse IP lookup is used to ensure that the emails we receive are coming from a valid sender and not from spammers. In addition to this, the reverse IP lookup tool also ensures that your IP has a PTR associated with it, and makes sure that your email does not end up in your recipient's spam folder.