This is a great project where he is collecting DNS records for as much as the Internet as he can manage with some really creative methods. Currently he has turned on PTR record searching. So let’s say you are doing a pen test or joining a new organization. You need to gather what information is available for the domain you are being employees to help. Just put the domain in quotes up in the search field and you will get back the resulting records. The search results are limited to 1,000 records by default but can be increased to up to 10,000. Small personal domains may not show up. It is giving great results for larger more established domains for organizations.
Just dump as many of the records you can. Drop it in a text file and grep with fun words like ldap, dc, mail, ftp etc can speed up your learning curve.