What's the purpose of Internet Protocol v4 (IPv4) addresses and subnet masks?

The Finder doesn't show items with periods at the beginning of their filenames or items with the hidden file flag enabled. Both methods for hiding items can only be managed from the command line interface.

The master password is used to reset local account passwords.

The Internet Protocol (IP) address identifies the location of a specific network device. IP addresses are the primary identification used by the Internet protocol suite TCP/IP for both local area and wide area networks. Subnet masks are used by network devices to identify their local network range and to determine whether outgoing data is destined for a network device on the LAN.

The Ping tab of Network Utility allows you to test basic connectivity to another network host by sending and then waiting for the return of a ping packet.