IPv4_address_exhaustion IP address exhaustion is the decreasing supply of unallocated IPv4 addresses. This depletion has been a concern since the 1980s when the Internet started to experience dramatic growth. As a result, this has been the driving factor in creating and adopting several new technologies, including classful networks, Classless Inter-Domain Routing (CIDR) methods, network address translation (NAT) and a new version of the Internet Protocol, IPv6.