The NDIS subkey stores configuration data for the Network Driver Interface Specification (NDIS) interface in Windows 2000, Ndis.sys.
Ndis.sys supports communication between protocol drivers, network interface drivers, and network adapters. It acts as an intermediary between protocol drivers and network adapters, so that they can remain independent. This allows a network adapter to support multiple network protocols, such as TCP/IP and Internetwork Packet Exchange (IPX). It also allows multiple network interface drivers and multiple network adapters to co-exist within a system.