Where is a recursive DNS query used?
Recursive DNS queries are most commonly applied in statistical software. When a website is visited, the web browser sends the IP address to the web server. This IP address can then be logged on the web server, after which a reverse DNS query can be used to determine through which access provider the visitor is connected at the moment he or she visited the website.
Reverse DNS queries are also used for security purposes of websites. For example if the admin environment has been violated by a hacker, the IP address can be logged. The webmaster can then trace this IP address by means of a recursive DNS query and discover through which provider or network the hacker connected to the website.