"arpa." YourDictionary, n.d. Web. 15 October 2018. <http://www.yourdictionary.com/arpa>.
arpa. (n.d.). Retrieved October 15th, 2018, from http://www.yourdictionary.com/arpa
.arpa - Computer Definition
Pronounced dot arpa. The generic Top Level Domain (gTLD) reserved exclusively for Internet infrastructure purposes.This is an unsponsored domain named for the Advanced Research Project Agency (ARPA). See also ARPANET, gTLD, Internet, and unsponsored domain.