For network devices, the process of booting over a local area network (LAN) and booting over a WAN is slightly different. In both network boot scenarios, the PROM downloads the booter from a boot server or an install server, which is inetboot in this case.
When booting over a LAN, the firmware uses DHCP to discover either the boot server or the install server. The Trivial File Transfer Protocol (TFTP) is then used to download the booter, which is inetboot in this case.
When you are booting over a WAN, the firmware uses either DHCP or NVRAM properties to discover the install server, the router, and the proxies that are required for the system to boot from the network. The protocol that is used to download the booter is HTTP. In addition, the booter's signature might be checked with a predefined private key.