Subnetting Made Easy (Part 2)

This post is the sequel of “Subnetting Made Easy (Part 1)” so let’s repeat our “magic table”:

128	192	224	240	248	252	254	255

In CCNA (or Networking quizzes) you have an IP Address in this format: 192.168.1.1/30 and you need to find, Network, Broadcast and Subnet Mask. All of this should be done in 45 seconds. How can we do and how the previous table can help us?

Let’s start to analyze the address: 192.168.1.1/30; 30 – 24 is 6 and our sixth position is 252; so our Subnet Mask will be 255.255.255.252.

Let’s calculate the Network and the Broadcast address:

256 – 252 = 4 so we’ll have just 4 address, from 0 to 3 (this case was really simple one). At the end our answer should be:

IP Address: 192.168.1.1/30
Network: 192.168.1.0
Broadcast: 192.168.1.3
Subnet Mask: 255.255.255.252

Let’s try something else: 210.32.25.76/26:

We know that /24 is 255.255.255.0; and 26 – 24 is 2 so our Subnet Mask will be 255.255.255.192

256 – 192 = 64 so our IP ranges will go from 0 – 63 and from 64 up to 127 to sumarize:

IP Address: 210.32.25.76/26
Network: 210.32.25.64
Broadcast: 210.32.25.127
Subnet Mask: 255.255.255.192