| Exam 200-120 | Question id=52 | WAN Technologies | 
        Which is the default encapsulation for serial interfaces on Cisco routers?
      
| A. | HDLC | |
| B. | PPP | |
| C. | SLIP | |
| D. | ISL | |
| E. | dot1q | |
| F. | Frame Relay | |
| G. | ADSL | |
| H. | X.25 | 
Default encapsulation is HDLC which is by default enabled on all cisco router.