Q: What is WINS and how is it different from DNS?

A: Like DNS, the Windows Internet Name Service (or WINS) included with Windows NT Server is dedicated to name resolution. However, WINS is concerned primarily with NetBIOS names, not DNS names. The NetBIOS name is the name that you assign to every Windows NT (or Windows 95, or Windows for Workgroups) machine when you install the operating system. NetBIOS names are sixteen characters in length. Windows NT pads out shorter names to fifteen characters and uses the sixteenth character for a control code that identifies the type of resource that the name represents.

When you use TCP/IP for Windows network communications, the NetBIOS name of a destination system must be converted to an IP address before any data can be transmitted to that system, just as a host name must be resolved by a DNS server. WINS is a database service that registers the NetBIOS names of the systems on a Windows network as they log on, and maintains a record of those names and their equivalent IP addresses. In the same way that a web browser uses DNS calls to resolve the host names you specify in URLs, file management utilities like Windows Explorer resolve the NetBIOS names of other Windows NT systems on the network in order to access their shared files. In fact, these two name resolution processes are intertwined. You can use the NetBIOS name of a web server on your network in a URL just as you would its DNS host name.

WINS is designed for use on private internetworks and, therefore, does not have to be nearly as scaleable as DNS, which must support literally millions of systems. Most networks that use WINS maintain multiple WINS servers, for purposes of load balancing and fault tolerance, but unlike DNS, each WINS server contains a complete record of all of the systems on the network. Each WINS server can be configured to replicate its data to the other servers on the network, so that all are kept up to date.

For more information, see page 382 of TCP/IP Administration.