Editing IPv4 (section)

==Assistive protocols==
IP addresses are not tied in any permanent manner to networking hardware and, indeed, in modern [[operating system]]s, a network interface can have multiple IP addresses. In order to properly deliver an IP packet to the destination host on a link, hosts and routers need additional mechanisms to make an association between the hardware address{{efn|For [[IEEE 802]] networking technologies, including [[Ethernet]], the hardware address is a [[MAC address]].}} of network interfaces and IP addresses. The [[Address Resolution Protocol]] (ARP) performs this IP-address-to-hardware-address translation for IPv4. In addition, the reverse correlation is often necessary. For example, unless an address is preconfigured by an administrator, when an IP host is booted or connected to a network it needs to determine its IP address. Protocols for such reverse correlations include [[Dynamic Host Configuration Protocol]] (DHCP), [[Bootstrap Protocol]] (BOOTP) and, infrequently, [[reverse ARP]].