When you’re ready to take the CCNA exam and get this coveted Cisco certification, you should really be prepared for various types of binary and subletting questions Cisco may throw at you. You must also be familiar with the different behavior, where the mask cannot be disclosed, and that’s where your knowledge of the notation prefix notation is entering another way of expressing the value of the subnet mask, as opposed in decimal format more familiar dotted. Not only will you see the prefix notation in the documentation for Cisco, but you can see on your CCNA exam.
Believe it or not, the two values are exactly the same. The first mask written in decimal notation is more familiar, and you know watching the first three bytes that each bit is set to “1″, because such a maximum value is 255 bytes.
The second value is the mask exactly the same, only this value is expressed in prefix notation. This particular value would be pronounced “slash 24″ and 24 represent the number of successively arranged in the subnet mask.
