What is the purpose of IGMP in a multicast implementation?()
A. it is not used in multicast
B. it determines the virtual address group for a multicast destination
C. it dynamically registers individual hosts in a multicast group on a specific LAN
D. it is used on WAN connections to determine the maximum bandwidth of a connection
E. it determines whether Bidirectional PIM or PIM sparse mode will be used for a multicast flow
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MgO和CaO同属NaCl型结构,而它们与水作用时则CaO要比MgO活泼,试解释之。
二级水准测量当采用DSZ1型水准仪进行其他各次沉降观测时可采用()。
A. 往返测
B. 单程观测
C. 单程双测站
将1NF的关系模式转变为2NF的关系模式,是消除了非主属性对主码的()