Network enumeration
Network enumerating is a computing activity in which user names, and info on groups, shares and services of networked computers are retrieved. It should not be confused with Network mapping which only retrieves information about which servers are connected to a specific network and what operating system is run on them.
Software
Network enumerators are computer programs often used to retrieve much info. Network enumerators are often used by script kiddies for ease of use, aswell as by more experienced hackers in cooperation with other programs/manual lookups. Also, whois queries, zone transfers, ping sweeps and traceroute can be performed. [1]