Learn to subnet in your head in just seconds! If you like what you see, check out Cisco Enterprise Networks: Basic Networking and IP Fundamentals.

Whenever a tech fad comes to an end, it becomes so obvious why it failed. Yet during the hype, it’s easy to miss the problems lurking just below the surface. I want to explore some of the problems I see with public blockchain and why I think it’s not going to live up to the hype. Blockchain can’t track real things …

Certifications are often lambasted as “worthless pieces of paper” and “experience is more important.” But for some people, certifications are more important than experience. A substitute for experience Newcomers to the IT world face the classic problem: how do you get experience without a job? Sure, you can tinker …

I think it’s time to stop using the term “network function virtualization”. Why? Because it doesn’t exist, at least not in the way the term suggests. The term is a category error, and when people try to make sense of the term, confusion and frustration ensue. Think of it like this: what’s the difference between a …

If you haven’t learned IPv6 yet, well, you’re not the only one. In December 2016, IPv6 (as we know it today) turned 18 years old. Children who were in the womb when RFC 2460 was being drafted are now old enough to vote, get married, and purchase firearms in some states. In honor of IPv6’s 18th birthday, allow me to …

The pre-release of my new book, Learn Cisco Network Administration in a Month of Lunches, is available from Manning Publications’ early access program. The book is a tutorial designed for beginners who want to learn how to administer Cisco switches and routers. Set aside a portion of your lunch hour every day for a …

I recently ran into a bizarre issue with users not being able to launch applications from a very old Citrix Presentation Server 4.0 farm when trying to launch from Citrix Web Interface 5.4. They were getting the eminently unhelpful, “An error occurred while making the requested connection.” The Diagnosis In the web …

One of the biggest scams of the Internet is in full swing right now. You may have heard of it. It’s called “net neutrality.” Fundamentally, net neutrality is about preventing Internet service providers (ISPs) from throttling or blocking traffic or providing paid prioritization of certain content. In addition, specific …