A.Enable the switch to participate in routing updates from external devices with the router command in global configuration mode.
B.Enter the no switchport command to disable Layer 2 functionality at the interface level.
C.Each port participating in routing of Layer 3 packets must have an IP routing protocol assigned on aperinterface level.
D.Routing is enabled by default on a multilayer switch， so the port can become a Layer 3 routing interface by assigning the appropriate IP address and subnet information.

A.ease of IP address assignment versus use of external routers
B.redundancy from trunking between distribution layer switches
C.provides first-hop redundancy to clients
D.allows inter-VLAN communication without requiring complexity of routing protocols