Understanding this formula is crucial to passing IT exams such as the Cisco CCNA and also in real life networking. Many networking emergencies could have been avoided by planning for future requirements during the design stage.
IN THE REAL WORLD: When planning a network addressing scheme always ask the client what their expected growth for the next few years is and account for that. Never design a network addressing scheme for what they have now.
Given a network ID and subnet mask, how many subnets can we form and how many hosts are there per subnet?
It all boils down to the powers of two.
255.255.224.0
11111111.11111111.11100000.00000000
[16 bits ] [3 bits] [13 bits]
[Network] [Subnet] [Host]
So in the class B example above we have three subnet bits to use and we can use every combination of three binary numbers to make up different subnets.
No comments yet
Leave A Reply (No comments So Far)