Subnet mask is somewhat complex, but simply put, it truncates the IP address to specify an individual computer within the subnet. The usual setting for Subnet Mask is 255.255.0.0. If information was directed to 180.23.3.54, the subnet mask would truncate that address to specify computer 3.54 in subnet 180.23.0.1. Telnet is another network utility, used for logging into a remote computer. For instance, one might want to use his Athena account from his home computer.
Finger is a useful utility for obtaining information about a user on the network.
The information one can obtain from finger varies from site to site, but usually it includes the user's real name, phone number, and last time they logged in. Ping is a program used to test out a certain IP address. It sends data to the specified site, which in turn sends it back. The sender computer then reports whether or not the remote site is functional based on whether it received the same data it sent. Ping proves most useful in troubleshooting situations, such as during the installation of an ethernet card or a new network drop.