Network enumeration tends to use overt discovery protocols such as ICMP and SNMP to gather information.
The next stage of enumeration is to fingerprint the operating system of the remote host.
Ethical hackers often also use the information to remove the glitches and strengthen their network.
Network enumerators are often used by script kiddies for ease of use, as well as by more experienced hackers in cooperation with other programs/manual lookups.
Also, whois queries, zone transfers, ping sweeps, and traceroute can be performed.