I think you're mistaking BOOTP with UDP. UDP is a communications paradigm that deals with how data is sent and received, where BOOTP is a fleshed out structured protocol providing services (BOOTP is the predecessor of DHCP). BOOTP/DHCP rely on the underlying UDP transport to provide their services. Also I think you're confused because I've never heard anyone refer to UDP as the "boot strap protocol" before - BUT I have heard people refer to BOOTP as the "boot strap protocol".