How can an ISDN interface be used as a backup link for a primary interface and still use DDR to communicate with other sites?
A. By using dialer profiles.
B. An ISDN interface cannot be both.
C. With the command backup interface serial 0/0 on the bri0/0 interface along with normal DDR commands.
D. With the command backup interface bri 0/0 on the physical interface and normal DDR commands on the bri0/0 interface