You can boot an ESXi host from a network interface. The network boot process varies depending on whether the target host is using legacy BIOS or UEFI firmware, and whether the boot process uses PXE TFTP, iPXE HTTP, or UEFI HTTP.

When you boot a target host, it interacts with the different servers in the environment to get a network adapter, boot loader, kernel, IP address for the kernel, and finally an installation script. When all components are in place, installation starts, as shown in the following illustration.

Figure 1. Overview of PXE Boot Installation Process
The PXE boot ESXi installation process is shown as a sequence of interactions between the ESXi host, the DHCP server, the TFTP server, the Web server, and the scripts depot. These interactions provide the ESXi host with an IP address for the virtual network adapter, the network boot loader, the kernel, the IP address for the kernel, and the installation script.

The interaction between the ESXi host and other servers proceeds as follows:

  1. The user boots the target ESXi host.
  2. The target ESXi host makes a DHCP request.
  3. The DHCP server responds with the IP information, the location of the TFTP or HTTP server, and the filename or URL of the initial network boot loader.
  4. The ESXi host contacts the TFTP or HTTP server and requests the filename or URL that the DHCP server specified.
  5. The TFTP or HTTP server sends the network boot loader, and the ESXi host runs it. The initial boot loader might load additional boot loader components from the server.
  6. The boot loader searches for a configuration file on the TFTP or HTTP server, downloads the kernel and other ESXi components as specified in the configuration file, and boots the kernel on the ESXi host.
  7. The installer runs interactively or using a kickstart script, as specified in the configuration file.