2022 Update: If you want a clear technical explanation of the OSI model, click on the cover of my book CCNP Enterprise Certification Study Guide: Implementing and Operating Cisco Enterprise Network Core Technologies for a free preview of Chapter 1 which explains each layer of the OSI model in intricate detail.

I …

Puzzled by networking on AWS? Check out my AWS networking deep dive series!

AWS Networking Deep Dive: Route 53 DNS

Configure Route 53 for any domain name, and configure health checks and routing policies.

AWS Networking Deep Dive: Virtual Private Cloud (VPC)

Create secure and scalable VPCs. Implement multi-VPC …

You probably know the popular Google DNS server IP addresses by heart: 8.8.8.8 and 8.8.4.4. Before those were around you might have even used Level3’s 4.2.2.1 and 4.2.2.2. Of course, everyone else uses these too, which means these popular servers are under a pretty heavy load.

Fortunately, there are faster public DNS …

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.

Cisco CCNA Routing and Switching learning path on Pluralsight

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 …