may additionally self-configure additional addresses on receipt of router advertisement messages, thus eliminating the need for a DHCP server. Both IPv4 and IPv6 hosts may randomly generate the host-specific part of an autoconfigured address. IPv6 hosts generally combine a prefix of up to 64 bits with a 64-bit EUI-64 derived from the factory-assigned 48-bit IEEE MAC address. The MAC address has the advantage of being globally unique, a basic property of the EUI-64. The IPv6 protocol stack also includes duplicate address detection to avoid conflicts with other hosts. In IPv4, the method is called link-local address autoconfiguration. However, Microsoft refers to this as Automatic Private IP Addressing (APIPA) or Internet Protocol Automatic Configuration (IPAC). The feature is supported in Windows since at least Windows 98. Name service discovery Internet protocols use IP addresses for communications, but these are not easy for humans to use; IPv6 in particular uses very long strings of digits that are not easily entered manually. To address this issue, the internet has long used DNS, which allows human-readable names to be associated with IP addresses, and includes code for looking up these names from a hierarchical database system. Users type in domain names, such as example.org, which the computer's DNS software looks up in the DNS databases to retrieve an IP address, and then hands off that address to the protocol stack for further communications. Looking up an address using DNS requires the IP address of the DNS server to be known. This has normally been accomplished by typing in the address of a known server into a field in one of the devices on the network. In early systems, this was normally required on every device, but this has been pushed up one layer in the hierarchy to the DHCP servers or broadband devices like cable modems that receive this information from their internet service provider. This has reduced the user-side administration requirements and provides a key element of zero-configuration access. DNS was intended to provide uniform names to groups of devices within the same administration realm, such as example.org, provided by a name service. Assigning an address to a local device, e.g., thirdfloorprinter.example.org, normally requires administrator access to the DNS server and is often accomplished manually. Additionally, traditional DNS servers are not expected to automatically correct for changes in configuration. For instance, if a printer is moved from one floor to another it might