*This post is for people who know about subnetting and are studying for the CCNA.
Once you start practicing for the CCNA in subnetting, you’ll realize that there are a few things you’ll have to memorize cold to do it quickly:
- The Binary Subetting Table
- All of the multiples of 2, 4, 8, 16, 32, 64, and 128 up to 256 for each
- The magic number from a subnetted subnet mask octet (e.g. 255.255.248.0 magic # is 8 )
- How many subnets and hosts per subnet for the given subnet mask
You have to be able to look at an IP address and subnet mask and in less than 10 seconds be able to determine the resident subnet of that IP address.
