Should I disable NetBIOS over TCP/IP on my Windows Server?

NetBIOS is an ancient session-level interface and transport protocol developed by IBM to network together PCs. It is a broadcast-based, non-routable and insecure protocol, and it scales poorly mostly because it was designed with a flat namespace.

The legacy (Windows 9x or Windows NT) machines need NetBIOS to function properly on a network because they use NetBIOS to logon to domains, find one another, and establish sessions for accessing shared resources.

Windows resolves a NetBIOS name to an IP address in three ways:

• a lookup in the LMHOSTS file
• a broadcast on the local subnet
• a request to a WINS server

Since Windows 2000, DNS has become the default name resolution method for Windows-based networks. To improve performance, it's recommended that you disable NetBIOS over TCP/IP on your network NIC and other dedicated-purpose NICs, such as for iSCSI, Live Migration and Clustering.

To disable NetBIOS over TCP/IP, access the IPv4 properties of your network adapter. To do this, open the Network and Sharing Center, select Change Adapter Settings, right-click the network connection, and select Properties. Select Internet Protocol Version 4 (TCP/IPv4) and click the Advanced button in the displayed dialog.Select the WINS tab and select the Disable NetBIOS over TCP/IP.

Additionally, make sure you enable jumbo packets on all network adapters, if you haven't done so already. Make sure you don't disable Client for Microsoft Networks and File and Printer Sharing for Microsoft Networks on the NICs.

Problems

• Computers Running Windows 2000

The computer no longer listens for traffic to the NetBIOS datagram service at User Datagram Protocol (UDP) port 138, the NetBIOS name service at UDP port 137, or the NetBIOS session service at Transmission Control Protocol (TCP) port 139.

If the computer needs to participate in WINS as a client, it must be physically multihomed (that is, it must have other physical network connections active and available for its use) for it to continue communicating with and using a WINS server.

• Computers Operating as WINS Clients

The computer can no longer function as a WINS server to service WINS clients over the connection unless NetBT is re-enabled.

For those adapters to use WINS, you must either manually configure a list of WINS servers on the NetBT-enabled connections or provide such a list to these connections from a DHCP server.