1. 255.0.0.0
2. 255.255.240.0
3. 12 bits (get a nice ratio of subnets to hosts instead of 10. Also allows for growth)
4 & 5.
Code:
ID Host Range Broadcast
112.0.0.0 112.0.0.1 - 112.0.15.254 112.0.15.255
112.0.16.0 112.0.16.1 - 112.0.31.254 112.0.31.255
112.0.32.0 112.0.32.1 - 112.0.47.254 112.0.47.255
112.0.48.0 112.0.48.1 - 112.0.63.254 112.0.63.255
112.0.64.0 112.0.64.1 - 112.0.79.254 112.0.79.255
112.0.80.0 112.0.80.1 - 112.0.95.254 112.0.95.255
112.0.96.0 112.0.96.1 - 112.0.111.254 112.0.111.255
112.0.112.0 112.0.112.1 - 112.0.127.254 112.0.127.255
I'm having several doubts about my calculations here. I need to practice more.