You use the preboot execution environment (PXE) to boot a host and launch the ESXi installer from a network interface.
ESXi 5.x is distributed in an ISO format that is designed to install to flash memory or to a local hard drive. You can extract the files and boot using PXE.
PXE uses DHCP and Trivial File Transfer Protocol (TFTP) to boot an operating system over a network.
PXE booting requires some network infrastructure and a machine with a PXE-capable network adapter. Most machines that are capable of running ESXi have network adapters that are able to PXE boot.
Ensure that the Auto Deploy server has an IPv4 address. PXE booting is supported only with IPv4.