Gary A. Donahue

Gary A. Donahue

Areas of Expertise:

  • network architecture
  • project management
  • documentation
  • networking
  • speaking
  • consulting
  • speaking
  • training
  • writing
Gary A. Donahue is a working consultant who has been in the computer industry for 27 years. Gary has worked as a programmer, mainframe administrator, Technical Assistance Center engineer, network administrator, network designer, and consultant. Gary has worked as the Director of Network Infrastructure for a national consulting company and has been the president of his own New Jersey consulting company; GAD Technologies.

Having designed and built networks ranging from simple LANs to world-wide converged VoIP networks, Gary has worked with people from all levels of IT and management. From small local businesses to Fortune 500 clients Gary observed many misunderstandings regarding routing and switching technologies, even among people with high-level certifications. Gary's goal as a consultant has always been to help his clients understand the technology at hand. Over the years he has written many documents outlining complex technologies in order that others might better understand. Much of this knowledge has been transformed into this book.

Being a teacher by nature, Gary enjoys the process of imparting newfound understanding to others. Gary has taught Tae Kwon Do, Photography and Astronomy both informally and through professional schools. Being someone who disdains boredom, Gary has many hobbies including amateur radio, astronomy, bicycling, computers of all kinds, gadgets, guitar, hiking, home theater, martial arts, photography, SCUBA diving, and competitive shooting. Gary is the owner of the Newf-Net Newfoundland Dog forum and is the author of the Newf-L F.A.Q.

Arista Warrior Arista Warrior
by Gary A. Donahue
Second Edition July 2019
Print: $69.99
Ebook: $59.99

Network Warrior Network Warrior
by Gary A. Donahue
Second Edition May 2011
Print: $59.99
Ebook: $50.99

Network Warrior Network Warrior
by Gary A. Donahue
June 2007
Ebook: $35.99

Gary A. blogs at:

"Any advanced computer collection needs this in-depth technical guide."
--James A. Cox, The Midwest Book Review: California Bookwatch, September 2011, Volume 6, Number 9

"I would recommend this book to anyone interested in enterprise networking – ranging from the relatively professionally uninitiated like myself (I only do networking administration for Computer Science House at the Rochester Institute of Technology) to those who are just transitioning from networking classes to actual jobs, who will benefit perhaps the most from the book's tips and tricks from a person in industry, or even the average middle-aged network administrator, who may find a large portion of the book a snooze, but likely still pick up a trick or two that was previously unknown."
--Chris Lockfort, Computer Science House

"Donahue has successfully created a thorough guide and reference that contains gems of wisdom and practical information for both new and experienced network engineers and others who need to understand complex computer networks."
--Chris Masotti, The Capital Letter, Sacramento Chapter Society for Technical Communication

"My hat goes off to Donahue as he accomplishes what many have tried in the past. If you manage a network infrastructure this book will remain on your desk, not your shelf."
--Central Oregon Information Systems User Group

"Well thought out examples were plentiful, along with anecdotes from the author, usually showing the consequences of doing things wrong. The illustrations did a great job of conveying the point at hand. Even though I've been doing this stuff for a while I learned several time saving techniques that I've already been able to put to use. This is a great book for people just getting into the industry, with their CCNA or without. It offers practical advice rather than dry textbook like explanations which is a welcome change. Even those with a few years of experience under their belt will be happy reading through Network Warrior. "
--Sean Walberg,

"Network Warrior does not offer everything IT admins need to know, as it focuses on Cisco equipment and the TCP/IP protocol. While some may seek a guide that covers additional network equipment and protocols, the author points out how such a far-reaching manual would be unwieldy. The book serves as a well-written and exhaustive guide that should be mandatory reading for new junior CCNA administrator hires. For those with experience in the field, the book is a worthy reference guide that can fill in gaps of knowledge you may have forgotten."
--Bruce Gain, Processor: Products, News & Information Data Centers Can Trust

"Donahue leverages his knowledge and the practical examples he includes in this text and aims all of that at the CCNA level (or higher) "network warrior" who wants to know what happens after they've passed the test. He takes all of the concepts a person studying for the CCNA learns about such as VLANs, EIGRP, and CIDR and puts real muscle and skin on their bones. He takes many other things the CCNA exam may not require such as converged networking, PIX Firewall configuration, and server load-balancing and does the same thing. The book takes some pretty dry material and manages to liberally moisten it so that reading the content gives a more lubricated feel and less of "metal-on-metal". It also isn't afraid to render the author's personal opinions about how to do things which may or may not be the "Cisco way"...Donahue's Network Warrior isn't designed to help you pass a test. It's designed to help you pass real life. Whether you're a newbie fresh out of school and looking for your first job, or an experienced technician looking for a better way to make sense of what you do, this book will be a real asset to you in your education and your career."
--James Pyles, Tech-Unity

"I particularly enjoyed that the author illustrates many concepts with mistakes and missteps he made himself. This isn't ivory tower networking, this is a guy who trips over cables and knocks out a whole company. Networking from A-Z. Switches, routers and hubs, oh my. Everything you need to know and then some. Worth the money, worth twice the money, maybe worth three times the money. Buy it."
--A.P. Lawrence, Information and Resources for Unix and Linux Systems

"I don't normally write reviews, so that in itself should mean something. This book is great for anyone who wants to get an overview of many aspects of networking, or for the current professional who wants an easy to understand refresher. The details given are just enough to keep you interested and learning, but not too much that it will leave you bored and confused. This book covers a lot more than a CCNA level person would know, so I consider it a great step if you're working on a CCNP, or just interested in deciding what topic you should master next. It also covers a lot of real-world material, which is usually not in most other Cisco books. This book is definitely worth the read!"
--Andy Page,

"Network Warrior is the best network administration book I've ever read...Gary Donahue has written a wonderful book that I highly recommend for anyone who administers, supports, or interacts with networks. Network Warrior may be the best book I will read in 2007. "
--Richard Bejtlich,