dnsmap was originally released back in 2006 and
was inspired by the fictional story "The Thief
No One Saw" by Paul Craig, which can be found
in the book "Stealing the Network - How to 0wn the Box".

dnsmap is mainly meant to be used by pentesters
during the information gathering/enumeration phase
of infrastructure security assessments. During the
enumeration stage, the security consultant would
typically discover the target company's IP netblocks,
domain names, phone numbers, etc ...

Subdomain brute-forcing is another technique that
should be used in the enumeration stage, as it's
especially useful when other domain enumeration
techniques such as zone transfers don't work.

WWW: https://tools.kali.org/information-gathering/dnsmap