In linguistics and grammar, a pronoun is a word that substitutes for a noun or noun phrase. It is a particular case of a pro-form.
IP Routing is an umbrella term for the set of protocols that determine the path that data follows in order to travel across multiple networks from its source to its destination. Data is routed from its source to its destination through a series of routers, and across multiple networks.
The Enhanced Interior Gateway Routing Protocol replaced the Interior Gateway Routing Protocol (IGRP) in 1993. One of the major reasons for this was the change to classless IPv4 addresses in the Internet Protocol, which IGRP could not support.