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

A.It checks the configuration register
B.It attempts to boot from a TFTP server
C.It loads the first image file in flash memory
D.It inspects the configuration file in NVRAM for boot instructions

A.access-list 50 deny 192.168.1.1 0.0.0.255
B.access-list 110 permit ip any any
C.access-list 2500 deny tcp any host 192.168.1.1 eq 22
D.access-list 101 deny tcp any host 192.168.1.1

A.ipv6 host
B.ipv6 unicast-routing
C.ipv6 local
D.ipv6 neighbor

A.For the two vlans to communicate，a network statement for the trunk interface needs to be added to the  OSPF configuration.
B.For the two vlans to communicate， a network statement for each subinterface needs to be  added  to the OSPF configuration.
C.Direct inter-vlan communication does not require OSPF
D.OSPF cannot be used if router-on-a-stick is configured on the router