### Supernetting and Binary System

Today, I want to show you how to change decimal to binary and SUPERNETTING.

## How to Change Decimal to Binary

It is so simple! You just need to divide decimal number by 2. The most important point is remainder. Let's do a sample. Find 12 in binary system.

12:2=6+0 As you see, the remainder is

**0**.
6:2=3+0 As you see, the remainder is

**0**.
3:2=1+1 As you see, the remainder is

**1**.
1:2=0+1 As you see, the remainder is

**1**.
Then lets write them down to up. (It is like Arabic.) So, it is 1100 in binary system.

## Understanding SUPERNETTING

Once I try to setup my Cisco Meraki, I had some problems with CIDR. If I put x.x.8.0/22, it works. However, it doesn't work for x.x.2.0/22. But x.x.2.0/23 works.

Then, I learned the supernetting.

Then, I learned the supernetting.

**The important point is where you catch the 1 for all subnetting. (When you AND them, it should be 1. Once you reached 1, you reach the max CIDR.) Please see below picture to understand easily.**__Explanation 1:__

__Explanation 2:__
If you thinking for x.x.x.x/24; you need to check the number at rank#24. If the ranges are 1, it is OK.

- For /24 CIDR, it is only 1 subnet; so every /24 CIDR will be fine.
- For /23 CIDR, there are 2 subnet (510 host); so you need to check the number at rank#23 for each subnet, they should be 1.
**Let me explain with an example:**

10.1.1.0/23: It has 2 subnet which are 10.1.1.1-10.1.1.254 and 10.1.2.1-10.1.2.254**10.1.1.0:**00000110.00000001.000000**0**1.00000000 =>Rank#23 is 0.**10.1.2.0:****1**0.00000000*=>Rank#23 is 1.***So,***10.1.1.0/23*can't be. Both rank#23 must be 1. - For /22 CIDR, there are 4 subnet (1022 host); so you need to check the number at rank#22 for each subnet, they should be 1.

__Explanation 3: (__

__Take the first 1 (number 1) from right side. And check below subnets on the same rank. You only can add as much as it is!__*Best Explanation:)*

**To see all numbers in binary, please click here.**

*P.S. This sample is for Class C Subnet. (255.255.xxx.0)*
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