Hello Rick
Yes you’re right. Let me say it another way. The 192.168.0.0/24 network defines a range of IP addresses from 192.168.0.0 to 192.168.0.255. This is a single subnet with a subnet mask of 255.255.255.0. If you started off with a range of 192.168.0.0/16 (which is the full range of private class C addresses), and you want to separate this range into /24 subnets, then this means that you can have up to 256 networks with 256 addresses (254 without network and broadcast) in each. In other words, the networks would be:
192.168.0.0/24
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
192.168.4.0/24
192.168.5.0/24
192.168.6.0/24
…
…
192.168.254.0/24
192.168.255.0/24
For this one, not quite. 255.255.255.240 is the same as /28. If we do the same thing here we will have
172.30.0.0/28
172.30.0.16/28
172.30.0.32/28
172.30.0.48/28
…
…
172.30.255.224/28
172.30.255.240/28
This one is a little harder to see. Looking at the IP address in binary, like you described yourself, we start off with:
10101100.00000011.00000000.00000000
where the italics are the subnet and the bold are the host. The italics are 12 bits, so 2^12 = 4096. We have 4096 subnets each containing 16 (14 without network and broadcast) hosts.
I hope this has been helpful!
Laz