In this video, Bill Ferguson applies the first three steps of the four-step process to a Class B subnetting example. Learn how to determine the new subnet mask and network size without converting to binary.
- [Instructor] We can apply the exact same four steps…to a Class B problem as well.…So, in this example,…we have a network, 172.16.0.0/16.…That's one network,…but we don't want one network.…We want 60 subnets.…What we want to know is…what would our subnet mask need to be,…how many hosts would we have per subnet,…and then what are the actual addresses…that will be on the subnets?…So applying the four-step method,…the first question is…where am I now?…That is not answered by the IP address.…
It's answered by the subnet mask.…With a /16, that tells me…that we are at the end of the second octet,…right before the third octet,…in a hole between those two bits.…So now the question is,…moving from the left toward the right,…how many bits…do I need…in order to create 60 subnets?…So, as you'll remember,…the formula is that two to the power of s has…to be greater than or equal to the number of subnets.…
So, in this case, two to the power of s…has got to be greater than or equal to 60.…Solve for s,…and you get s equal to six.…So, so what?…
Discover how IP addresses are constructed and how to understand them better by relating them to a picture rather than converting binary numbers or memorizing charts. Learn the benefits that subnetting in your head provides in every aspect of IT networking, including routing protocols, access control lists, and network address translation. Then walk through Bill's four-step method, which leverages the rules that were used to create the original classful IP addressing schemes. Using this method, students can learn to "see" the IP addresses for each subnet. Watch the technique in action, and then practice what you've learned using the audio guides in chapter five, which provide auditory cues as you subnet in your head.
- The benefits of subnetting
- Class A, B, and C IP addressing
- The four-step subnetting method
- Troubleshooting IP topologies and IP host address ranges
- Audio cues for the four-step method