Which two design concerns must be addressed when designing a multicast implementation？（）

• 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