To PXE boot the ESXi installer, the DHCP server must send the address of the TFTP server and the filename of the initial boot loader to the ESXi host.

When the target machine first boots, it broadcasts a packet across the network requesting information to boot itself. The DHCP server responds. The DHCP server must be able to determine whether the target machine is allowed to boot and the location of the initial boot loader binary, typically a file on a TFTP server.

Caution: Do not set up a second DHCP server if your network already has one. If multiple DHCP servers respond to DHCP requests, machines can obtain incorrect or conflicting IP addresses, or can fail to receive the proper boot information. Talk to a network administrator before setting up a DHCP server. For support on configuring DHCP, contact your DHCP server vendor.

Many DHCP servers can PXE boot hosts. If you are using a version of DHCP for Microsoft Windows, see the DHCP server documentation to determine how to pass the next-server and filename arguments to the target machine.

Example of Booting Using TFTP with IPv4

This example shows how to configure an ISC DHCP server to boot ESXi using a TFTP server at IPv4 address xxx.xxx.xxx.xxx. 

#
# ISC DHCP server configuration file snippet.  This is not a complete
# configuration file; see the ISC server documentation for details on
# how to configure the DHCP server.
#
allow booting;
allow bootp;
option client-system-arch code 93 = unsigned integer 16;
class "pxeclients" {
   match if substring(option vendor-class-identifier, 0, 9) = "PXEClient";
   next-server xxx.xxx.xxx.xxx;
   if option client-system-arch = 00:07 or option client-system-arch = 00:09 {
      filename = "mboot.efi";
   } else {
      filename = "pxelinux.0";
   }
}

When a machine attempts to PXE boot, the DHCP server provides an IP address and the location of the pxelinux.0 or mboot.efi binary file on the TFTP server.

Example of Booting Using TFTP with IPv6

This example shows how to configure an ISC DHCPv6 server to boot ESXi using a TFTP server at IPv6 address xxxx:xxxx:xxxx:xxxx::xxxx. 

#
# ISC DHCPv6 server configuration file snippet.  This is not a complete
# configuration file; see the ISC server documentation for details on
# how to configure the DHCP server.
#
allow booting;
allow bootp;
option dhcp6.bootfile-url code 59 = string;
option dhcp6.bootfile-url "tftp://[xxxx:xxxx:xxxx:xxxx::xxxx]/mboot.efi";

When a machine attempts to PXE boot, the DHCP server provides an IP address and the location of the mboot.efi binary file on the TFTP server.

Example of Booting Using HTTP with IPv4

This example shows how to configure an ISC DHCP server to boot ESXi using a Web server at IPv4 address xxx.xxx.xxx.xxx. The example uses gPXELINUX for legacy BIOS hosts and iPXE for UEFI hosts. 

#
# ISC DHCPv6 server configuration file snippet.  This is not a complete
# configuration file; see the ISC server documentation for details on
# how to configure the DHCP server.
#
allow booting;
allow bootp;
option client-system-arch code 93 = unsigned integer 16;
class "pxeclients" {
   match if substring(option vendor-class-identifier, 0, 9) = "PXEClient";
   next-server xxx.xxx.xxx.xxx;
   if option client-system-arch = 00:07 or option client-system-arch = 00:09 {
      if exists user-class and option user-class = "iPXE" {
         # Instruct iPXE to load mboot.efi as secondary bootloader
         filename = "mboot.efi";
      } else {
         # Load the snponly.efi configuration of iPXE as initial bootloader
         filename = "snponly.efi";
      }
   } else {
      filename "gpxelinux.0";
   }
}

When a machine attempts to PXE boot, the DHCP server provides an IP address and the location of the gpxelinux.0 or snponly.efi binary file on the TFTP server. In the UEFI case, iPXE then asks the DHCP server for the next file to load, and this time the server returns mboot.efi as the filename.

Example of Booting Using HTTP with IPv6

This example shows how to configure an ISC DHCPv6 server to boot ESXi using a TFTP server at IPv6 address xxxx:xxxx:xxxx:xxxx::xxxx. 

#
# ISC DHCPv6 server configuration file snippet.  This is not a complete
# configuration file; see the ISC server documentation for details on
# how to configure the DHCP server.
#
allow booting;
allow bootp;

option dhcp6.bootfile-url code 59 = string;
if exists user-class and option user-class = "iPXE" {
   # Instruct iPXE to load mboot.efi as secondary bootloader
   option dhcp6.bootfile-url "tftp://[xxxx:xxxx:xxxx:xxxx::xxxx]/mboot.efi";
} else {
   # Load the snponly.efi configuration of iPXE as initial bootloader
   option dhcp6.bootfile-url "tftp://[xxxx:xxxx:xxxx:xxxx::xxxx]/snponly.efi";
}

When a machine attempts to PXE boot, the DHCP server provides an IP address and the location of the snponly.efi (iPXE) binary file on the TFTP server. iPXE then asks the DHCP server for the next file to load, and this time the server returns mboot.efi as the filename.