In this video, Bill Ferguson provides audio queues to use the four-step subnetting method to determine the subnet addresses and host ranges given an address from one of the subnets. Review this video as you practice subnetting in your head.
- [Bill] Starting with an IP address and a subnet mask,…determine the number of subnets and hosts per subnet.…Start by looking at the first octet of the IP address.…If this were a classful address,…would this be Class A, Class B, or Class C?…Use this to determine the classful subnet mask.…
This reverse engineers the answer to step one,…where am I now, or in this case,…where would the classful network range begin?…Then determine how many extra bits…the subnet mask contains as compared…to its classful subnet mask.…Now apply the formula to determine the number of subnets,…which is two to the power of S,…where S is the number of subnet bits…that have been added to the classful subnet mask.…
Now apply the formula to determine…the number of hosts per subnet,…which is two to the power of H minus two,…where H is the number of host bits that are remaining.…You've now reverse engineered the subnetted address…to determine the number of subnets…and the number of hosts per subnet.…
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