WINS

Successfully maintaining a Windows NT Server–based network means using every tool that you have on your shelf. In the world of Windows NT Server 4.0, Windows Internet Naming Service (WINS) is one of those tools. Note that WINS will be displaced by Dynamic DNS in Windows 2000 Server, so in reality, you could say that WINS is on its way out of favor. And although Windows 2000 Server will support WINS for backward compatibility reasons, at this point in the Windows NT Server 4.0 life cycle, you are advised to plan for DNS-based network name resolution and to deemphasize your reliance on WINS.

That said, this section will provide you with what you need to know about WINS. It will provide little more given WINS’ impending exit from the Windows NT community. And although you certainly need to know WINS basics, be advised that your time is better spent mastering the first two topics of this chapter (DNS, DHCP).

WINS was designed to eliminate broadcasts and maintain a dynamic database providing computer name–to–IP address mappings.

Note: The key point with WINS is its “dynamic” paradigm. Its database is updated dynamically or on the fly. By contrast, DNS maintains a static database of addresses that may only be upgraded by receiving a propagated delta DNS database periodically.

A WINS system has two components: servers and clients.

• WINS servers. WINS servers maintain the database that maps a WINS Client IP address to its NetBIOS computer name. Broadcasts for NetBIOS-type name resolutions are eliminated (or at least reduced) because the database on the WINS server may be consulted for immediate name resolution.
• WINS clients. A WINS client is a workstation that is configured with the WINS server(s) IP address(es). At system startup, the WINS client registers its name and IP address with the WINS server. When a WINS client needs a name resolved, the WINS server and its database are consulted. This results in fast and efficient name resolution.

At the enterprise level, a network typically has one or more WINS servers that a WINS client may contact for name resolution. In fact, WINS servers may be configured on a given network so that they replicate all computer names to IP address mappings to each other’s respective databases.

Implementing WINS Server on your Windows NT Server network results in the following benefits:

• Reduced broadcast network traffic
• No need for an LMHOSTS file
• Dynamic name registration
• No duplicate computer names
• No specific need for a DNS server (although dispensing with one is not recommended!)

How WINS Works

Out of the box, when you configure a Windows NT Server–based network to use WINS for its name registration, it adheres to the h-node broadcasting methodology. You will recall the h-node refers to one of the NetBIOS over TCP/IP modes that defines how NBT identifies and accesses resources on a network.

During name resolution, the WINS client:

• Checks to see if it is the local machine name.
• Looks at its cache of remote names. Any name that is resolved is placed in a cache, where it remains for 10-minutes.
• Attempts to contact the WINS server.
• Attempts broadcasting.
• Checks the LMHOSTS file (if it is configured to use and check the LMHOSTS file).
• Last, tries the HOSTS file and then DNS (if appropriately configured).

You will recall that this process was previously discussed early in the chapter in the “Be Resolved” section.

Note: If a DHCP client has been configured to use m-node name resolution, the client first attempts to broadcast. The WINS server is consulted second.

When a WINS client boots, a Name Registration Request packet is sent to the WINS server so that the client computer name may be registered. As many Name Registration Request packets are sent as necessary to register names. Not surprisingly, these packets contain the WINS client’s IP address and name.

Installing WINS servers

You may elect install a WINS server when you are initially setting up your Windows NT server or at a future date. In order to set up a WINS server, you must be logged on as a member of the Administrator group.

STEPS:
To install a WINS server
Step 1.	Choose the Network applet in Control Panel. The Network dialog box appears.
Step 2.	Select the Services tab sheet in the Network dialog box.
Step 3.	Click the Add button. The Select Network Service dialog box appears.
Step 4.	Select Windows Internet Name Service in the Select Network Service dialog box.
Step 5.	Windows NT Server displays the Windows NT Setup dialog box asking for the complete path to the Windows NT Server distribution. Type in the correct path and click Continue.
Step 6.	Observe that the Windows Internet Name Service appears as one of the Network Services listed on the Service tab sheet of the Network dialog box. Click Close.
Step 7.	Restart the computer. When the computer restarts, the WINS server is ready to receive name registrations and resolve name requests.

Note that the WINS service will be configured to start automatically. It may be stopped via the Services applet in Control Panel.

Configuring WINS servers

You will use the WINS Manager located in the Administrator Tools (Common) program group to configure your local and remote WINS servers on your network.

The left pane of WINS Manager displays the WINS servers visible on your network. Typically these are shown as IP addresses, but it is entirely possible that the WINS server list will display NetBIOS names (if that is what the specific server supplied). If indeed a computer name is supplied, then WINS Manager establishes a connection to the WINS server via named pipes.

STEPS:
To configure a WINS server
Step 1.	Select the Configuration command from the Server menu.
Step 2.	Click the Advanced button to expand the WINS Server Configuration dialog box.
Step 3.	Configure the WINS Server Configuration dialog box.

Note that advanced WINS configuration topics such as configuring replication partners are considered to be beyond the scope of this book given WINS’ limited life before the release of Windows 2000 Server and its Dynamic DNS solution. If you are interested in advanced WINS configuration topics, I recommend that you consult the Windows NT Server 4.0 Resource Kit or Microsoft TechNet.

Configuring WINS clients

If a client workstation has TCP/IP installed, it may be configured to use a WINS server to perform its computer name–to–IP address resolution. This is accomplished when the client workstation is configured with the IP addresses of the primary and secondary WINS servers.

WINS Server on Windows NT Server 4.0 can support the following WINS clients:

• Windows NT Server 4.0
• Windows NT Workstation 4.0
• Windows 98
• Windows 95
• Windows for Workgroups 3.11 (WFW) with the Microsoft 32-bit TCP/IP VxD installed.

Note: WFW is one of the clients supported on the Windows NT Server 4.0 CD-ROM in the \i386\clients\msclient directory. This is also one of the clients that is supported and configured via the Network Client Administrator application found in the Administrative Tools (Common) program group. Note this client support also extends to the next two clients (Microsoft Network Client for MS-DOS and LAN Manager for MS-DOS 2.2c).

• Microsoft Network Client for MS-DOS with real-mode TCP/IP driver
• LAN Manager for MS-DOS 2.2c

If a DHCP server is used to supply TCP/IP configuration information to DHCP clients, such TCP/IP configuration may contain the following WINS configuration information:

• 044 WINS/NBNS servers configured with an IP address of one or more WINS servers
• 046 WINS/NBT Node Type set to 0x1 (b-node), 0x2 (p-node), 0x4 (m-node), or 0x8 (h-node). For detailed information on node types, you should consult the Windows NT Server Resource Kit or Microsoft TechNet.

Using WINS Manager

The great thing about WINS Manager is that after its initial configuration, it becomes a reporting tool for you to observe WINS server–related name resolution activity. This service essentially runs itself.

To see detailed information about the current WINS server, select Detailed Information from the Server menu. The Detailed Information dialog box appears. Select the Close button to dismiss the Detailed Information dialog box.

Since in all likelihood you and I are both going to be living with Windows NT Server 4.0 for the foreseeable future either as the primary NOS or as a background NOS to Windows 2000 Server, it is prudent to drop down to the WINS engineering level and educated ourselves on the detailed statistics that are reported back from WINS.

Windows NT WINS

WINS converts Windows computer names to IP addresses but does not do name lookups based on IP addresses. The use of Windows Explorer or NET commands invokes the NetBIOS interface. NetBIOS names, if repeated on another domain that is on the network, may cause a problem since there is no way to distinguish NetBIOS names between two domains. Each computer, when booted, sends a name registration broadcast. If there is no response, the computer will use the name it registered. A NetBIOS broadcast releases the computer name when the computer is shutdown gracefully.

WINS reduces this broadcast traffic when using NBT. The registration and release is sent to the WINS server rather than being broadcast. The clients have the IP address of the WINS server and they are configured to use WINS before using NetBEUI broadcasts. A backup WINS server may be available on the network for fault tolerance.

NetBIOS Names

On the WINS server, there is a NetBIOS name for each service a NetBIOS computer offers. This uses the 16th hidden character of the NetBIOS names. The characters and their meanings are:

• 00 - Workstation service (Domain name) or (Workgroup name) or (Computer name)
• 03 - Messenger service (Computer name) or (User name)
• 06 - RAS server service (Computer name)
• 1B - Primary domain controller (Domain name)
• 1C - Domain controller or PDC or BDC (Domain name)
• 1D - Master browser (Domain name)
• 1E - Only is on servers, indicates the computer would become a browser if requested.. (Domain name) or (Workgroup name)
• 1F - NetDDE service (Computer name)
• 20 - Server service (Computer name)
• 21 - RAS client (Computer name)
• BE - Network Monitoring Agent service (Computer name)
• BF - Network monitor utility service (Computer name)

Most computers such as workstations have a minimum of Computer name (00) and Workgroup name (00). Also the Messenger service computer name and user name are registered.

Starting WINS

WINS service is installed from the control panel network applet services tab. The computer must be restarted after the installation. The Microsoft WINS Manager which may be run from any NT computer on the network is used to configure WINS. To configure WINS, only statically assigned IP addresses on your network must be entered. This is done by selecting "Mappings" from the menu and clicking on the "Add Mappings" button.

WINS Purpose

The purpose of WINS is to allow a NetBIOS name to be converted to an IP address. Therefore computers using WINS must be using NBT (NetBIOS over TCP/IP). WINS was originally put in place to compensate for a shortcoming of NetBEUI which is the fact that it is not routable. Therefore on large Networks IP is used to transport NetBIOS and rather than using broadcasts, information is sent to the WINS server. In fact, although WINS overcomes a shortcoming in Microsoft networking, it can actually be used to solve another problem.                                                                                               

The problem concerns the dynamic allocation of computer addresses with DHCP. When DCHP allocated addresses to computers, that information is not currently sent to DNS servers. Therefore it is not possible using doman name service (DNS) to get an IP address based on a computer name for a computer that had its IP address assigned using DHCP. WINS solves this problem since when NetBIOS computers come up, they send their name and IP address information to the WINS server. The WINS server keeps this information updated and responds to name queries with IP addresses similar to DNS. Under the DNS configuration tab in the networking control panel, "Enabling DNS for WINS Resolution" allows DNS to ask the WINS server to help resolve IP addresses that DNS cannot resolve. This can be more easily implemented on the DNS server side by allowing the DNS server to use WINS. See the DNS section for details.

WINS Operation

When a NetBIOS broadcast is to go out, a computer sends over TCP/IP to a WINS server to resolve NetBIOS names. WINS dynamically builds its database. When a client uses WINS it announces to the WINS server over TCP/IP rather than broadcasting to all computers. WINS Message Modes:

• Client Name Registration - When a client service is started, the appropriate NetBIOS name for that service (Using the hidden 16th byte) is sent to the WINS server. If the primary WINS server fails to respond, the request is sent to the secondary WINS server after three tries. If no WINS server responds, B-node broadcasts are used by the client. When contacted, the WINS server returns a time to live (TTL) field containing the length of time the client may use that name. If a duplicate name is received, a challenge is sent by the server to the registered client. If the current owner responds, the new client request is rejected.
• Client Lease Renewal - When the name lease is at 50%, the client sends a name renewal request to the WINS server with its name and IP address. When the lease is 7/8 up, the client will try again then attempt a lease with the secondary WINS server. After 4 attempts with the secondary WINS server, it attempts lease renewal with the primary WINS server again.
• Client Name Release - The client sends a name release message with its name and IP address. the server responds with a positive release message. If no confirmation is received by the client a NetBIOS broadcast release is sent up to three times.
• Server Name Query and Name Resolution response - With WINS server on the network, resolution is done using H-node on UDP port 137 (NetBIOS Name Service). Name query order:
1. Local cache
2. WINS server (primary then secondary, two times).
3. Broadcast
4. Lmhosts file
5. Hosts file
6. DNS

Pentium, 200Mhz computer can process 1500 name registrations and 750 queries per minute. 10,000 clients can be serviced with two WINS servers. Non-WINS clients names and IP addresses must be added to the WINS server lmhosts file.

The WINS manager inport function can import lmhosts files. Keywords other than "#DOM" are ignored. #DOM lines are added to a group for the specified domain. WINS Manager mappings menu, "Static Mappings" selection. Tyoes of mappings:

• Unique
• Group - Domains and workgroups are specified
• Domain Name
• Internet Group
• Multihomed

 

WINS Manager

A menu selection is "Mapping", "Show Database". Static mappings can be added to WINS for clients that are static and /or are not Windows clients or servers. WINS database replication may be manually performed using the WINS manager.

WINS Client Support

• NT Server 5.5+ and 4.0
• NT Workstation 3.5+ and 4.0
• Windows 95
• WFW with TCP/IP-32
• Microsoft Network Client 3.0 for DOS
• Lan Manager 2.2c for DOS

No OS/2 Lan manager support.
Client Configuration types:

• 044 - WINS/NBNS Servers
• 046 - WINS/NBT Nde to 0x8 (H-node)

A WINS proxy agent can be configured to act as a relay for non-WINS clients. One WINS proxy is used on each subnet that has non-WINS clients. This means that machines that are not using WINS (Even Windows machines such as those without TCP/IP) can use a proxy agent to let them find resources on other subnets. There should be a maximum of two proxy agents per subnet. The agent must be a Windows based client, not a server. When NetBIOSs names are registered, both the proxy agent and the WINS server checks the name. The proxy agent is configured at the following registry location:

Hkey_Local_Machine\System\CurrentControlSet\Services\NetBT\Parameters

Set the Enable Proxy parameter to REG_DWORD value of 1 and restart the computer.

WINS Replication

When two WINS servers are configured to communicate with each other replication occurs any time the data base on one of them changes. Servers are configured as a push or pull partner. A server can be both a push and pull partner. Push partners send update notices when a database change is made. A pull partner asks push partners for database entries more recent than their current listings. Only changes are replicated. Pull servers are used across slow links since pull requests can be set for specific times.

• A pull server will pull updates when it is started, then at chosen times thereafter.
• A push partner will send updates when a change threshold is reached. A thershold and update interval may be set.

WINS database replication may be manually performed using the WINS manager. If multicasting is supported on the network WINS servers can multicast to 224.0.1.24 every 40 minutes. WINS server partnerships are on by default. The values "UseSelfFndPnrs" and "McastIntvl" are used to set partnership on or off and the multicast interval.

To add replication partners, the menu item "Server" and "Replication Partners" is selected using the WINS Manager. The "Configure" button is used to set replication intervals, retry counts, and the number of changes before sending updates. The WINS Configuration menu controls:

• Renewal interval - Default of 96 hours, sets the amount of time between which a client must renew its name.
• Extinction Interval - Default of 96 hours - Time between when a name is released and marked as extinct.
• Extinction Time-out - Default of 96 hours with a 24 hour minimum. Time between when a name is marked as extinct and removed from the database.
• Verify Interval - Default of 576 hours (24 days). - The interval between which WINS entries owned other WINS servers are verified.

The "Advanced" button allows the following selections:

• Logging enabled - WINS database events are logged
• Log Detailed Events - The amount of detail in the database is set.
• Replicate Only with Oartners - Enabled by default, this will allow a pull server to send to WINS servers it is not set as a partner to.
• Backup On Termination - When WINS Manager is closed, the database is backed up.
• Migrate On/Off - Static entries are changed to dynamic when a conflict between a static and dynamic entry is found.
• Starting Version Count - Only needed if the database becomes corrupt, this is an ID number for the database.
• Database Backup Path - A local path for the database to be backed up to.

Database entry types:

• \\Comupter name 00h - Workstation service
• \\Comupter name 03h - Messenger service
• \\Comupter name 20h - Server Service
• \\User Name 03h - The logged on user name
• \\Domain name 1bH