Technically speaking…

Microsoft has supported a combination of the Domain Name Service (DNS) and the Windows Internet Naming Service (WINS) for quite a long time. Beginning in Windows Server 2000, the primary naming service was DNS and the Microsoft WINS efforts were becoming lesser needed.

In Windows Server 2008 the need for WINS has been essentially eliminated, although it remains supported for backward compatibility. In place of WINS, for the latest server version of Windows Microsoft has introduced Link Local Multicast Resolution (LLMR). This tip will discuss LLMR and the benefits this new naming method brings to the table.

The Windows Internet Naming Service was a good method for allowing Windows client and server computers to communicate using NetBIOS names. This technology works well within local networks that use only IPv4 addresses.

LLMR provides peer to peer address resolution, supports both IPv4 and IPv6 addressing, and can function without a WINS or DNS server being present. Because it operates only on a local level LLMR does not replace the functionality of DNS.

Windows Server 2008 and Windows Vista support LLMR which is designed to resolve computer names when there is not another service available to do so, such as in the following scenarios:

• Ad Hoc networks
• Small Office or Home networks
• Corporate environments where DNS is not available

It is in these instances where LLMR can really improve name resolution and allow client and server computers to function more efficiently. LLMR is enabled on any systems running Windows Vista or Windows Server 2008 and when used, the name resolution works as follows:

A host computer requests information from its preferred local DNS server, if this request fails it attempts the request against the configured alternate DNS server. If this attempt fails, the request fails over to LLMR.

The host computer sends a multicast request for an IP address for the computer name being looked up over UDP.

Note: The request is only sent to computers on the same subnet.

Computers that support LLMR, those running Vista and Windows Server 2008, receive the LLMR request and compare the computer name to their own host name. If the computer name does not match the host name of a recipient host, the request is discarded. On the other hand, if the host name being looked up matches one of the local computers a unicast response is returned containing the matching computers IP address.

There are no configuration steps needed to use this new technology, since it is enabled by default in Windows Vista and later, however it can be disabled in the registry. The LMMR also supports reverse lookups; it handles these lookups by sending a unicast query to an IP address requesting the host name.

Note: LLMR requires computer names to be unique on the local subnet.

Link Local Multicast Resolution is a much better application for name resolution than WINS because it supports the up and coming IPv6 technology as well as existing IP technologies.