When a device on a TCP/IP network starts up and is not configured for a static IP address, it needs to receive an IP address before it can communicate with other devices on the network. A standard computer with a hard disk can be enabled for static configuration but a diskless device that does not have any storage, only has an option to acquire an IP address from the network. This process of getting a new machine up and running is commonly referred to as bootstrapping. To provide this functionality, the TCP/IP Bootstrap Protocol (BOOTP) was created.
The Bootstrap Protocol, or BOOTP, is a network protocol used by a network client to obtain an IP address from a configuration server. In order to get an IP address the network clients contact other devices on the network. Initially (ages ago) a boot floppy disk had to be inserted to establish the initial network connection, but later on Network Interface card manufacturers embedded the protocol in the ROM of the interface card as well as on motherboards that have onboard network adapters, thereby avoiding the need for floppy disks and allowing for direct network booting.
During the bootstrap process when a computer is starting up, the BOOTP protocol is used. A BOOTP server assigns an IP address to each client from a pool of addresses and based on the configuration of the server. BOOTP generally uses the User Datagram Protocol (UDP) as the transport protocol. Earlier, BOOTP has also been used for diskless workstations to obtain the network location of their boot image in addition to an IP address using protocols like PXE, and also by enterprises to roll out pre-configured client installations to newly installed PCs.
Although BOOTP provides a very important function, it is not used frequently today and has been superseded by DHCP (Dynamic Host Configuration Protocol) which is a more advanced protocol for the same purpose. Most DHCP servers also offer BOOTP support and are the most prevalent method used today to assign IP addresses to diskless workstations and clients that require IP addresses.
BOOTP is dead and buried… But I have a friend who uses it in his test lab