Gather DNS information about the target is of vital information when conducting a penetration testing. DNS mapping information can reveal the internal architecture of the organizations IT infrastructure.

Darknet or Dark Web is the part of the internet which is hidden to normal users, and unlike the normal everyday internet it is, if not 100%, 99% anonymous...

The term Darknet or Dark Web are commonly used interchangeable with Deep Web. Their is a significant difference in these two.