A.The neighboring router stops receiving ACK packets from this router
B.The neighboring router starts receiving route updates from this router
C.The neighboring router is too busy to answer the query （generally caused by high CPUutilization）
D.The neighboring router is having memory problems and cannot allocate the memory to processthe query or build the reply packet

A、The first 23 bits of the multicast MAC address are 0x01-00-5E. This is a reserved value thatindicates a multicast application
B、The last 3 bytes （24 bits） of the multicast MAC address are 0x01-00-5E. This is a reservedvalue that indicates a multicast application
C、To calculate the Layer 2 multicast address， the host maps the last 23 bits of the IP address intothe last 24 bits of the MAC address. The high-order bit is set to 0
D、The first 3 bytes （24 bits） of the multicast MAC address are 0x01-00-5E. This is a reservedvalue that indicates a multicast application