ISI became one of the earliest nodes on ARPANET,[23] the predecessor to the Internet, and in 1977 figured prominently in a demonstration of its international viability.[24] ISI also helped refine the TCP/IP communications protocols fundamental to Net operations,[3] and researcher Paul Mockapetris developed the now-familiar Domain Name System characterized by .com, .org, .net, .gov, and .edu[25] on which the Net still operates. (The names .com, .org et al. were invented at SRI International, an ongoing collaborator.)