A.802.1Q native VLAN frames are untagged by default.
B.802.1Q trunking ports can also be secure ports.
C.802.1Q trunks can use 10 Mb/s Ethernet interfaces.
D.802.1Q trunks require full-duplex, point-to-point connectivity.
E.802.1Q trunks should have native VLANs that are the same at both ends.

A.it is a layer 2 messaging protocol which maintains vlan configurations across network.
B.it includes an 8-bit field which specifies the priority of a frame.
C.it is used exclusively for tagging vlan frames and dose not address network reconvergence following switched network topology changes.
D.it modifies the 802.3 frame header，and thus requires that the FCS be recomputed.
E.it is a trunking protocol capable of carring untagged frames.

A.255.255.255.0
B.255.255.255.192
C.255.255.255.250
D.255.255.255.252

A.RSTP cannot operate with PVST+.
B.RSTP defines new port roles.
C.RSTP defines no new port states.
D.RSTP is a proprietary implementation of IEEE 802.1D STP.
E.RSTP is compatible with the original IEEE 802.1D STP.

A.redundant
B.spanned
C.provisioned
D.converged