If you are an information technology or cybersecurity professional, and you are planning to study for and take a networking certification such as CompTIA’s Network+ or Cisco’s CCENT, CCNA, or CCNP, then you will need to know and understand IP addressing, subnetting, and supernetting inside and out. When I was studying for the CCNA years ago, I put together a set of subnetting spreadsheets, and eventually shared it on my two principal websites. You can find them at on the Reference Desk page. The Ref Desk page is very frequently visited, according to Google Analytics.
I was introduced to an outstanding article that covered this issue better than anything I have ever read on the subject, including most of the official certification text books. I was asked to include a link to this article, and since I use this page all the time when teaching a networking class, I was happy to make the addition.
Steven Cooper is the author responsible for The Ultimate Guide to Subnetting – plus 10 Best Subnet Calculators and Cheat Sheet. The article covers the following topics:
- 1 Why subnet?
- 2 What is subnetting?
- 3 Broadcast address and network address
- 4 The subnet mask
- 5 Subnetting shortcuts
- 6 Variable-length subnet masking
- 7 The Best Subnet Calculators
- 8 Master IP Subnetting
- 9 Subnetting Cheat Sheet
I know many of my students have struggled with the concepts of IP addressing, subnetting, and classless interdomain routing (CIDR). Even if you have been working in IT or networking for a while, you still might appreciate the depth and clarity that Steven brings to a subject that has bedeviled many of us at some point in our careers. Give it a read.
Share
JUL
About the Author:
I am a cybersecurity and IT instructor, cybersecurity analyst, pen-tester, trainer, and speaker. I am an owner of the WyzCo Group Inc. In addition to consulting on security products and services, I also conduct security audits, compliance audits, vulnerability assessments and penetration tests. I also teach Cybersecurity Awareness Training classes. I work as an information technology and cybersecurity instructor for several training and certification organizations. I have worked in corporate, military, government, and workforce development training environments I am a frequent speaker at professional conferences such as the Minnesota Bloggers Conference, Secure360 Security Conference in 2016, 2017, 2018, 2019, the (ISC)2 World Congress 2016, and the ISSA International Conference 2017, and many local community organizations, including Chambers of Commerce, SCORE, and several school districts. I have been blogging on cybersecurity since 2006 at http://wyzguyscybersecurity.com