Wins Study Guide

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Weds Evening TCP/IP Class

Chapter 8 Windows Internet Name Service (WINS) Study Guide

Request for Comments 1533, 1534, 1541, and 1542

Chapter Objectives:

Describe and use the NetBIOS name resolution methods

Set the order of NetBIOS name resolution

Install and configure WINS servers and clients

Add WINS servers to WINS Manager and monitor WINS

Configure and manage WINS servers

Replicate the WINS Database

Key Terms:

Nbstat – This is a useful utility related to NetBios over TCP/IP. Remember NBT stands for NetBios over TCP/IP and the STAT stands for statistics.

Positive Name Registration Response - If there is no NetBios name in the WINS server database, that is IDENTICAL to the one send in the name registration request, then the PNRR is sent by the server to indicate TTL.

Time-to-Live (TTL) – This indicates how long a client may own a NetBios name.

NetBios over TCP/IP – Protocol that enables NetBios (computer names) over a TCP/IP network.

NetBios Name – Microsoft computer name (up to 15 characters)

Advantages of WINS:

Automatically updates resolution database with new DHCP lease

Less broadcast traffic

WINS is the only truly dynamic name service. It creates a database of IP address-to-NetBIOS name mappings

Every time a computer running Windows NT, TCP/IP and NBT logs on to a network, it registers its NetBIOS name and IP address with the WINS server that is running on a Windows NT server. Thus this mapping is always current

The WINS database can be made current throughout a world wide network by making use of WINS Push and Pull partner servers to replicate databases that each server has created locally.

What is WINS:

WINS (Windows Internet Naming Service), part of the Microsoft Windows NT Server, manages the association of workstation names and locations with Internet Protocol addresses without the user or an administrator having to be involved in each configuration change. WINS automatically creates a computer name-IP address mapping entry in a table, ensuring that the name is unique and not a duplicate of someone else's computer name. When a computer is moved to another geographic location, the subnet part of the IP address is likely to change. Using WINS, the new subnet information will be updated automatically in the WINS table. WINS complements the NT Server's Dynamic Host Configuration Protocol (DHCP), which negotiates an IP address for any computer (such as your workstation) when it is first defined to the network. If you're a computer user on a network connected to a Windows NT Server, you may find WINS mentioned in some of your network-related programs or system messages.

Background:
This service works as a sort of NetBIOS name database. When clients are configured to use WINS, they automatically contact the WINS server when booted and tell it their NetBIOS name and IP address. The WINS server keeps track of this information. Then, when a client needs to resolve a NetBIOS name, it directly contacts the WINS server and asks for the IP address for that name. WINS responds with the information.

Installing WINS:

WINS installation is very similar to the installation of any other Windows NT networking service. Right-click on Network Neighborhood and select Properties. Click on the Services tab to show all the currently running networking services.

If "Windows Internet Name Service" isn't listed, click the Add... button. The Select Network Service window will appear - scroll through it until you see "Windows Internet Name Service". Click it, then click OK. You may be prompted for your Windows NT Server CD-ROM, and may also have to reboot your system.

WINS Configuration:

In its basic setup, WINS requires no real configuration. Immediately after installation, clients can be configure to use the WINS server. Configuration changes are normally only needed if you are using more than one WINS server on your network and want each of those servers to share their NetBIOS names database with each other.

For example, you may want to put two WINS servers on your network for fault-tolerance. Each client would be configured to use one of the servers as a primary and the other as a secondary. If the two WINS servers are set to replicate their database information with each other, then if one of the servers goes down for a bit, the other still has information on all the NetBIOS names. Additionally, if you have an extremely large network you might want to have multiple WINS servers just to keep the traffic on each one at reasonable level. Replicating the WINS information to all servers will make sure that any client can resolve any other client's NetBIOS name.

WINS configuration is handled through the WINS Manager program, accessed through Start Menu/Programs/Administrative Tools/WINS Manager. Replication is set up under the Server/Replication Partners menu option.

WINS Vs DNS:
WINS differs from DNS in two significant ways:

DNS information for a particular domain (i.e. indiana.edu) is configured through static configuration files. That is the files must be updated by hand for the most part. The WINS information database is built dynamically without human intervention. A WINS client will register its name with the WINS server when it boots. As long as the name if not already in use, the WINS server will allow the client to use that name.

Secondly, WINS and DNS are used to resolve different types of services. DNS is used to resolve service types like HTTP for web access, or FTP for file transfer, or POP for mail transfer, or TELNET for terminal access. WINS name resolution is used to resolve names of NETBIOS services. Some NETBIOS services would include a Win95 machine sharing a directory, or a WinNT server sharing a printer.

However, there are some overlapping circumstances.

Two examples:

A Windows NT machine can use DNS to resolve the name of a NETBIOS service.
A web browser (i.e. Netscape) can resolve a HTTP address through WINS via the Microsoft TCP/IP stack.

Comprehension Exercises:

If the computers on the network that you manage are only going to use the TCP/IP communications architecture, why would you ever want to use a WINS server?

Solution: Because workstations on my network obtain IP addresses from a DHCP server. I want DNS name resolution to have a dynamic WINS database of IP addresses available.

Suppose you use a DHCP server on your network that is not WINS-enabled. What is going to happen if a computer sends a message to one of your workstations using the DNS name of that workstation?

Solution: The computer that is sending the DNS query will most likely get back the wrong IP address because the DHCP server will have assigned it an address that is not the one in the DNS database. This is an important problem, which suggests that you use DHCP carefully.