According to MacTCP Engineering, MacTCP remembers what protocol was
successful in acquiring its IP address over startups, so that the
successful protocol is tried first. In other words, once MacTCP has
located and acquired an IP address from a BOOTP server it then uses the
BOOTP server before trying the RARP server the next time MacTCP is used.
The first time MacTCP is used, the RARP server may be tried first.
However, this should not continue once the BOOTP server is located.
There is currently no way to configure MacTCP to select server priority via
a control-panel device or by using ResEdit.