Introduction to WINS


In today's Internet-centric environment, the Transmission Control Protocol/Internet Protocol (TCP/IP) has become the ubiquitous networking protocol. For long-time Unix users, the re-emergence of TCP/IP is a good thing. TCP/IP came out of the Unix arena and has been the native protocol for Unix systems since the late 1980s.

Microsoft, on the other hand, opted to not use TCP/IP as the native networking protocol in early versions of Windows. Instead of TCP/IP, these early versions of Windows used NetBEUI as the native networking protocol. NetBEUI was a pretty good protocol for small networks; it required no configuration and didn't require complex addressing as TCP/IP does. However, NetBEUI can't handle routing and does not perform well in large environments. Therefore, Microsoft needed to add TCP/IP support.

When Microsoft began to add TCP/IP support to its LAN server products, the company ran into a little problem. The naming system used on Microsoft networks at that time would not function on routed TCP/IP networks. Microsoft LAN Manager computers used the computer's NetBIOS names for identification. Although this makes maintaining the network very simple for an administrator because servers are automatically located on the network by name, this naming system was a problem with the TCP/IP protocol.

NetBIOS has a design limitation that shows up in routed networks because NetBIOS relies heavily on broadcast messages to locate servers. Broadcast messages are messages that are processed by every computer on a network segment, rather than by a specific computer. This paradigm is usable on smaller networks but can add overwhelming amounts of broadcast traffic on an enterprise network. To confine the impact of broadcast messages on a TCP/IP network, IP routers do not forward broadcast messages. Therefore, Microsoft had to find a way to make NetBIOS naming work in a standard TCP/IP network.

Broadcasts Are Evil

In most corporate networks today, Ethernet switches are in use to help route and reduce traffic. Switches work by forwarding packets to only the hardware or MAC addresses for which they are intended. By doing this, it effectively improves the maximum speed of the network. However, broadcast traffic isn't sent to a single address; it's sent to every address and thus must be sent to every machine connected to the Ethernet switch. The end result is that the switch can't perform its function.

The more broadcast traffic that occurs on a network, the less effective an Ethernet switch is. Thus, in switched environments, as in most environments these days, reducing the number of broadcasts is critical.

Microsoft's first -solution, introduced in its older operating system called LAN Manager server, was to use a LAN Manager hosts (lmhosts) file on each computer on the network. Similar to the hosts file used before DNS was available, an lmhosts file consists of records matching NetBIOS names to IP addresses. When a computer couldn't find a particular NetBIOS computer on the local network, it would consult its lmhosts file to see whether the computer could be found elsewhere.

An lmhosts file is a text file that must be edited manually. After creating a master lmhosts file, an administrator must copy the file to every computer on the network. Every time a computer is installed or removed, the master lmhosts file must be updated and redistributed. Doesn't that sound like fun? (This might sound familiarthe architects of TCP/IP faced a similar issue with hosts files before the DNS specification was written.)

Microsoft also needed a dynamic name -service that would maintain a list of computers on the networka name service that could work in routed TCP/IP environments. Microsoft's answer was the Windows Internet Name Service (WINS), which functioned as a NetBIOS server. Four elements can be found in a WINS network:

  • WINS servers When WINS client computers enter the network, they contact a WINS server using a directed message. The client computer registers its name with the WINS server and uses the WINS server to resolve NetBIOS names to IP addresses.

  • WINS client computers WINS client computers use directed messages to communicate with WINS servers. All versions of Windows since Windows for Workgroups can be WINS client computers.

  • Non-WINS client computers Older Microsoft network client computers that can't use direct WINS communications can still benefit from WINS. Their broadcast messages are intercepted by WINS proxy computers that act as intermediaries between clients that must broadcast and WINS servers. MS-DOS and Windows 3.1 client computers function as non-WINS clients.

  • WINS proxies All versions of Windows client computers since Windows for Workgroups can function as WINS proxies. They intercept broadcasts on their local subnets and communicate with a WINS server on behalf of the broadcasting client computer.

Note: Configuring the WINS Proxy

Should you have a need to configure a WINS proxy within your environment, the task is an easy one. Simply open the Registry Editor on the Windows XP Professional or Windows Server 2003 computer to be configured as the WINS proxy and change the following key value to 1 (REG_DWORD):

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NetBT\Parameters\EnableProxy

After making this change, you will need to restart the TCP/IP NetBIOS Helper service on the computer.


As is discussed in the "Configuring WINS Replication." section later in this chapter, WINS servers can replicate their databases so that each WINS server can provide name resolution for the entire network. Whenever possible, it is desirable to have at least two WINS servers. This lets name resolution take place when one name server is down. It also lets administrators distribute WINS activity across multiple servers to balance the processing loads. WINS server addresses are one of the configuration settings that can be issued -with DHCP.




MCSA(s)MCSE 70-291(c) Implementing, Managing, and Maintaining a Microsoft Windows Server 2003 Network Infrastructure
MCSA/MCSE 70-291: Implementing, Managing, and Maintaining a Microsoft Windows Server 2003 Network Infrastructure (Exam Prep)
ISBN: 0789736497
EAN: 2147483647
Year: 2006
Pages: 196
Authors: Will Schmied

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