A. for multiple ISDN connections
B. for modem concentrated dial-up connections
C. for a group of users in the same vicinity sharing a connection
D. for use by mobile users

A. only the low-order 23 bits of the MAC address are used to map IP addresses
B. only the low-order 24 bits of the MAC address are used to map IP addresses
C. only the high-order 23 bits of the MAC address are used to map IP addresses
D. only the low-order 23 bits of the IP address are used to map MAC addresses
E. the 0x01004f MAC address prefix is used for mapping IP addresses to MAC addresses
F. the 0x01005e MAC address prefix is used for mapping IP addresses to MAC addresses