Learn to Subnet
Pay attention to whether the examples excludes or includes Subnet Zero. Do not get into the habit of assuming the expected result is for the usable hosts. We always include subnet zero when determining the total number of addresses in the subnet. Never subtract 2, for the network and broadcast addresses, unless specifically asked for usable hosts.
- Learn to Subnet (Charles C. Botsford)
- Chapter 4 – Subnetting (Microsoft Docs)
- IP Subnetting Made Easy: George Ou explains IP subnetting using his own graphical approach. It’s a great primer for students and a nice refresher for others. (TechRepublic.com)
- IP Addressing and Subnetting for New Users (Cisco.com)
- Understanding IP Addressing (by Chuck Semeria)
- Using /31 subnets on point-to-point links (PacketLIfe.net)
- Build Your Skills: Subnetting and supernetting IP networks
- Note: This article excludes subnet zero and the broadcast subnet for the whole address block, but we always include both in our calculations
Practice make improvement!
- SubnettingQuestions.com: Random Network, Broadcast, First, Last Addresses and Ranges
Use the calculators to check your work, not to do the work for you.