IPv6 Name resolution

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Name resolution

While IPv6 is designed to work with the 128-bit IPv6 addresses of the source and the destination hosts, computer users are likely to experience difficulty in using and remembering the IPv6 addresses of the computers with which they want to communicate. Unique names, which are easier to remember, can be used instead.

If a name is used as an alias for an IPv6 address, you need to ensure that the name is unique and that it resolves to the correct IPv6 address. The IPv6 protocol for the Windows Server 2003 family can use host names to resolve a name to an IPv6 address. Host names are used by programs that use Windows Sockets.

Host name resolution is successfully mapping a host name to an IPv6 address. A host name is an alias that is assigned to an IPv6 node, identifying it as an IPv6 host. The host name can be up to 255 characters long and can contain alphabetic and numeric characters, hyphens, and periods. You can assign multiple host names to the same host.

Windows Sockets (Winsock) programs can use one of two values for the destination to which you want to connect: the IPv6 address or a host name. When the IPv6 address is specified, name resolution is not required. When a host name is specified, the host name must be resolved to an IPv6 address before IPv6-based communication with a resource can begin.

Host names can take various forms. The two most common forms are a nickname and a domain name. A nickname is an alias for an IPv6 address that individuals can assign and use. A domain name is a structured name in a hierarchical namespace named Domain Name System (DNS). An example of a domain name is www.microsoft.com.

Nicknames or domain names are resolved through entries in the Hosts file, which is stored in the systemroot\System32\Drivers\Etc folder. For IPv6 name-to-address entries, the IPv6 address is written by using standard colon-hexadecimal format. For more information, see Expressing IPv6 addresses and TCP/IP database files.

Domain names are resolved by sending DNS name queries to a configured DNS server, which is a computer that either stores domain name-to-IPv6 address mapping records or has records of other DNS servers. The DNS server resolves the queried domain name to an IPv6 address and returns the results. The DNS client in Windows XP and the Windows Server 2003 family supports the processing of AAAA (quad-A) resource records. All DNS queries and responses are sent by using IPv6 and IPv4. DNS name devolution for fully qualified domain names is also supported. For more information, see DNS defined.