Adding More than Five IP Addresses to NIC in Windows NT

Ordinarily, you can set up to five IP addresses per network card installed, under the settings for TCP/IP (in Control Panel, double-click the Network icon, then click the Protocols tab; on the Protocols tab, select TCP/IP Protocols, then click the Properties button; on the IP Address tab, click Advanced...). However, it is possible to add more than five IP addresses to a network card by modifying the registry.

Windows NT 4.0 has no limitation on the number of IP addresses that can be bound to a NIC. The limitation is on system resources.

Use the Registry Editor (REGEDT32.EXE) to add your IP addresses and subnet masks, as follows:

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

1. Start REGEDT32.EXE and locate the following Registry subkey:
   
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Services\<Adapter Name>\Parameters\Tcp
2. Find the IPAddress value and double-click it.
3. The Multi-String Editor dialog box should appear with the IP address selected. Type each additional IP address on a new line within the dialog box, then click OK. For example:
   
   100.100.100.1
   100.100.100.2
   100.100.100.3
4. Find the SubnetMask value and double-click on it.
5. The Multi-String Editor dialog box should appear with the Subnet Mask selected. Enter each additional subnet mask on a new line within the dialog box, then click OK. For example:
   
   255.255.255.0
   255.255.255.0
   255.255.255.0
   
   IMPORTANT: The order of the IP addresses and subnet masks must correspond.
6. Exit REGEDT32.
7. Exit Windows NT and restart your computer.

You should have all of the IP addresses specified in the registry bound to your network cards.