单项选择题
A. global unicast
B. anycast
C. multicast
D. unspecified address
单项选择题 Which type of cable is used to connect the COM port of a host to the COM port of a router or switch?（）
单项选择题 Which Cisco Catalyst feature automatically disables the port in an operational PortFast upon receipt of a BPDU?（）
单项选择题 How many bits are contained in each field of an IPv6 address?（）