A.Access ports can only send tagged frames

B.Trunk port can only send untagged frames

C.Access port can only send untagged frames

D.Trunk ports can only send tagged frames

A.The switch works at the network layer

B.The router works at the network layer

C.The router works at the physical layer

D.The switch works at the physical layer

A.False

B.True

A.OSPFv1

B.OSPFv4

C.OSPFv3

D.OSPFv2

A.The firewall cannot implement network address translation

B.Firewall can realize access control between different networks

C.Firewall can realize user identity authentication

D.The firewall can isolate the network of unreachable security level