"In computer networking, the Bootstrap Protocol, or BOOTP, is a network protocol used by a network client to obtain an IP address from a configuration server. The BOOTP protocol was originally defined in RFC 951.
BOOTP is usually used during the bootstrap process when a computer is starting up. A BOOTP configuration server assigns an IP address to each client from a pool of addresses. BOOTP uses the User Datagram Protocol (UDP) as a transport on IPv4 networks only. Historically, BOOTP has also been used for Unix-like diskless workstations to obtain the network location of their boot image in addition to an IP address, and also by enterprises to roll out a pre-configured client (e.g., Windows) installation to newly installed PCs.
Originally requiring the use of a boot floppy disk to establish the initial network connection, manufacturers of network cards later embedded the protocol in the BIOS of the interface cards as well as system boards with on-board network adapters, thus allowing direct network booting. The Dynamic Host Configuration Protocol (DHCP) is a more advanced protocol for the same purpose and has superseded the use of BOOTP. Most DHCP servers also function as BOOTP servers."
RFC 951 is the basic bootstrap protocol that was designed to do little more than assign an IP address to a client along with a few other resources that could be vendor defined. I think RFC 1048 BOOTP extensions include a time offset field that specifies that time offset from UTC, but I'm not 100% certain.