# What are the rules to combine two networks to form a supernet? (CIDR, supernetting)

I know how it is done, but my professor is unable to explain me the core concept(bits and bytes).

For example, He said `200.1.0.0/24` and `200.1.1.0/24` can be combined to form a network with 500 IP addresses but `200.1.1.0/24` and `200.1.2.0/24` cannot!?

I am unable to understand his logic of some adjacent network and delta value (which is 2 here).

Can anyone explain ? Thanks in advance!!

The dotted decimal (x.x.x.x) notation is tripping you up. IP addresses are 32 bit binary numbers. The dotted decimal notation is only to make the numbers easier to read by humans. If you convert the addresses into binary, you'll see that your first example falls on a bit boundary, but your second example does not.

• Okay. That was as simple as I liked my professor to make it. Thanks Ron. And, Can you tell me where can I read more about Bit boundary and superneting concepts? Jun 13, 2017 at 15:31
• Rather than reading, do it. Convert the addresses to binary and compare them. What do you notice about the first pair vs the second pair of addresses? BTW, what you're really asking about is summarization. Supernetting is related to classful addressing, and that has been dead since before you were born. Jun 13, 2017 at 15:44

200.1.1.0/24 and 200.1.2.0/24 can also be supernetted, but due to the third octets' bit patterns ...01 and ...10 you'll need to remove two bits from the netmask, ie. 200.1.0.0/22 (200.1.0.0 through 200.1.3.255).