A.AC

B.STA

C.AP

D.Client

A.Set the authentication mode of PPP to CHAP

B.Add the user name and password of the authenticated party to the authenticating party's local user list

C.Configure the data link layer encapsulation type of the interface connected to the peer device to PPP

D.Configure the user name and password sent to the authenticating party on the authenticated party

A.Ports in Forwarding state can receive BPDU packets

B.The port in the Forwarding state will definitely send BPDU packets

C.The port in the Forwarding state does not learn the source MAC address of the packet

D.The port in the Forwarding state can forward data packets

A.3

B.1

C.2

D.4

A.Application layer protocol

B.Transmission Control Protocol

C.Internet Protocol

D.Network layer protocol