Calculating the Subnets.
I am using the online Subnet Calculator. Some Data displayed on the calculator and indicated by the Red arrows on the screenshot below need some explanation:
example:
how did they come with subnet bits: 12
Maximum subnets 4096
host per subnets :14
subnet ID :172.16.1.0
Broadcast address : 172.16.1.15
Thank you
You start with an address that has a 16-bit mask. You extend the mask to accommodate the number of subnets/hosts and you end up with a 28-bit mask.
28-16=12.
Actual mask minus the original (or starting) mask will give the size of the subnet field. Which in this case is 12.