Lab 1 Information Gathering


In the (new, browserbased) lab 1 with the title Information Gathering, Question #4 states: " What is the subdomain for which only reverse DNS entry exists for". In the solution of this lab, one of the subdomains is pointed out, without any explanation as to why this is the one asked for here. Can someone please elaborate as to why one should come to the conclusion that this is the one the quesiton asks for?