Saturday, October 27, 2012

Using Windows Internet Name Service

WINS is a service that resolves computer names to IP addresses. Using WINS, the computer name COMPUTER84, for example, can be resolved to an IP address that enables computers on a Microsoft network to find one another and transfer information. WINS is needed to support pre–Windows 2000 systems and older applications that use NetBIOS over TCP/IP, such as the .NET command-line utilities. If you don’t have pre–Windows 2000 systems or applications on the network, you don’t need to use WINS.

WINS works best in client/server environments in which WINS clients send single-label (host) name queries to WINS servers for name resolution and WINS servers resolve the query and respond. When all your DNS servers are running Windows Server 2008 or later, deploying a Global Names zone creates static, global records with single-label names without relying on WINS. This allows users to access hosts using single-label names rather than FQDNs and removes the dependency on WINS. To transmit WINS queries and other information, computers use NetBIOS. NetBIOS provides an application programming interface (API) that allows computers on a network to communicate. NetBIOS applications rely on WINS or the local LMHOSTS file to resolve computer names to IP addresses. On pre–Windows 2000 networks, WINS is the primary name resolution service available. On Windows 2000 and later networks, DNS is the primary name resolution service and WINS has a different function. This function is to allow pre–Windows 2000 systems to browse lists of resources on the network and to allow Windows 2000 and later systems to locate NetBIOS resources.

To enable WINS name resolution on a network, you need to configure WINS clients and servers. When you configure WINS clients, you tell the clients the IP addresses for WINS servers on the network. Using the IP addresses, clients can communicate with WINS servers anywhere on the network, even if the servers are on different subnets. WINS clients can also communicate by using a broadcast method through which clients broadcast messages to other computers on the local network segment requesting their IP addresses. Because messages are broadcast, the WINS server isn’t used. Any non-WINS clients that support this type of message broadcasting can also use this method to resolve computer names to IP addresses.

When clients communicate with WINS servers, they establish sessions that have the following three key parts:

» Name registration. During name registration, the client gives the server its computer name and its IP address and asks to be added to the WINS database. If the specified computer name and IP address aren’t already in use on the network, the WINS server accepts the request and registers the client in the WINS database.

» Name renewal. Name registration isn’t permanent. Instead, the client can use the name for a specified period known as a lease. The client is also given a time period within which the lease must be renewed, which is known as the renewal interval. The client must reregister with the WINS server during the renewal interval.
» Name release. If the client can’t renew the lease, the name registration is released, allowing another system on the network to use the computer name, IP address, or both. The names are also released when you shut down a WINS client.

After a client establishes a session with a WINS server, the client can request name resolution services. The method used to resolve computer names to IP addresses depends on how the network is configured. The following four name-resolution methods are available:

» B-node (broadcast). Uses broadcast messages to resolve computer names to IP addresses. Computers that need to resolve a name broadcast a message to every host on the local network, requesting the IP address for a computer name. On a large network with hundreds or thousands of computers, these broadcast messages can use up valuable network bandwidth.

» P-node (peer-to-peer). Uses WINS servers to resolve computer names to IP addresses. As explained earlier, client sessions have three parts: name registration, name renewal, and name release. In this mode, when a client needs to resolve a computer name to an IP address, the client sends a query message to the server and the server responds with an answer.

» M-node (mixed). Combines b-node and p-node. With m-node, a WINS client first tries to use b-node for name resolution. If the attempt fails, the client then tries to use p-node. Because b-node is used first, this method has the same problems with network bandwidth usage as b-node.

» H-node (hybrid). Also combines b-node and p-node. With h-node, a WINS client first tries to use p-node for peer-to-peer name resolution. If the attempt fails, the client then tries to use broadcast messages with b-node. Because peer-to-peer is the primary method, h-node offers the best perfor¬mance on most networks. H-node is also the default method for WINS name resolution.

If WINS servers are available on the network, Windows clients use the p-node method for name resolution. If no WINS servers are available on the network, Windows clients use the b-node method for name resolution. Windows computers can also use DNS and the local files LMHOSTS and HOSTS to resolve network names.

When you use DHCP to assign IP addresses dynamically, you should set the name resolution method for DHCP clients. To do this, you need to set DHCP scope options for the 046 WINS/NBT Node Type as specified in “Setting Scope Options”. The best method to use is h-node. You’ll get the best performance and have reduced traffic on the network.

Source of Information : Windows Server 2012 Pocket Consultant 2012

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