Network Boot Protocols in Windows 2000 RIS

In Microsoft Windows 2000, Remote Installation Services (RIS) allows administrators to deploy operating systems remotely across a network without requiring physical media. This article explains the primary network protocols used by RIS to initiate client boots, focusing on the Preboot Execution Environment (PXE) standard and the complementary network services—such as DHCP, TFTP, and BINL—that make remote system provisioning possible.

The Core Boot Protocol: PXE

Remote Installation Services relies on the Preboot Execution Environment (PXE) protocol to boot network clients. PXE is an industry-standard client/server environment built directly into the firmware (BIOS and Network Interface Card ROM) of compatible computers. It allows a bare-metal machine without an installed operating system or local storage image to locate a network boot server, acquire network parameters, and download bootable execution files.

How the Windows 2000 RIS Boot Process Works

The RIS boot workflow operates using a coordinated sequence of standardized and proprietary protocols:

1. Network Initialization via DHCP

When a PXE-enabled client starts up, it broadcasts a standard DHCP (Dynamic Host Configuration Protocol) DHCPDISCOVER packet. This packet includes specific PXE tags identifying the client as a network boot candidate. The DHCP server responds with an IP address, subnet mask, and DNS information.

2. Service Authorization via BINL

Simultaneously, the Windows 2000 BINL (Boot Information Negotiation Layer) service listens for these PXE broadcast requests. Integrated with Active Directory, BINL verifies whether the client machine is authorized to receive an installation. Once validated, the server responds with the network path and filename of the initial boot loader, typically Startrom.com.

3. Boot File Delivery via TFTP

After receiving the server location from BINL, the client initiates a transfer using TFTP (Trivial File Transfer Protocol). Because TFTP operates over UDP with minimal overhead, it is ideal for simple firmware-level network transfers. The client downloads Startrom.com and subsequently loads the Client Installation Wizard (Oscfilter.exe / OSChooser).

4. Setup Execution

Once the initial boot files run in memory, the client interfaces with the user or automated answer files. Subsequent operating system files and drivers are transferred using the SMB (Server Message Block) protocol over standard TCP/IP connections to complete the Windows 2000 setup.