A.DLCI 17 describes the ISDN circuit between R2 and R3.
B.DLCI17 describes a PVC on R2.It cannot be used on R3 or R1.
C.DLCI17 is the Layer 2 address used by R2 to describe a PVC to R3.
D.DLCI17 describes the dial-up circuit from R2 and R3 to the service provider.

A.show session
B.show cdp neighbors
C.show users
D.show queue

A.RIP requires less time to converge
B.RIP uses less bandwidth
C.RIP is less complex to configure
D.RIP demands fewer router resources
E.RIP has a more accurate metric

A.transport type all
B.transport output all
C.transport preferred all
D.transport input all

A.131.1.123.30
B.131.1.123.31
C.131.1.123.32
D.131.1.123.33