Structured Network Troubleshooting Methodology Step 3 Test the Theory to Determine the Cause by Anthony Sequeira

Before taking action on what you consider to be the most likely cause of a problem, do a sanity check on your theory. Would your hypothesized cause lead to the observed symptoms? In the example:

User A's computer is unable to communicate with server 1, as verified by a ping test. However, user A can communicate with all other servers. Also, no other user seems to have an issue connecting to server 1.

You might examine the subnet mask assigned to user A's computer and determine that it is incorrect. Specifically, the subnet mask makes user A's computer think that server 1 is on the same subnet as user A's computer. As a result, user A's computer does not forward to its default gateway when attempting to reach server 1.

If your hypothesis is technically sound, you can proceed to troubleshooting step 4, Establish a plan of action to resolve the problem and identify potential effects.

However, if you notice a flaw in your logic, you need to formulate an alternative hypothesis. The formation of an alternative hypothesis might involve escalating the problem to someone more familiar with the devices(s) in question.

Note: In troubleshooting, escalating means turning the problem over to someone with more experience or knowledge. In the above example, I'm assuming that Anthony meant to first consult with someone with more experience or knowledge as to their opinion of the logic of your hypothesis. As a network administrator you want to retain responsibly for your trouble ticket until you have to admit that it beyond your ability to resolve. You won't have much job security if you turn over lots trouble tickets without resolution.

Elaboration of Step 1 and Step 3 though Step 7 of the network troubleshooting methodology that should be understood and memorized for the Network+ exam can be found in CompTIA Network+ N10-008 Cert Guide

About The Author

Anthony Sequeira, CCIE No. 15626, is a Cisco Certified Systems Instructor (CCSI) and author regarding all levels and tracks of Cisco Certification. Anthony formally began his career in the information technology industry in 1994 with IBM in Tampa, Florida. He quickly formed his own computer consultancy, Computer Solutions, and then discovered his true passion-teaching and writing about Microsoft and Cisco technologies. Anthony joined Mastering Computers in 1996 and lectured to massive audiences around the world about the latest in computer technologies. Mastering Computers became the revolutionary online training company, KnowledgeNet, and Anthony trained there for many years. Anthony is currently pursuing his second CCIE in the area of Security and is a full-time instructor for the next-generation of KnowledgeNet, Anthony is also a VMware Certified Professional.

CompTIA Network+ N10-008 Cert Guide contains proven study features that allow you to succeed on the exam the first time. Expert instructor Anthony Sequeira shares preparation hints and test-taking tips, helping you identify areas of weakness and improve both your conceptual knowledge and hands-on skills, essential for successful completion of the performance-based testing items on the exam. This complete, CompTIA-approved study package includes the following:

A test-preparation routine proven to help you pass the exams
Clearly defined chapter learning objectives covering all N10-008 exam topics
Chapter-ending review questions and exam preparation exercises, which help you drill on key concepts you must know thoroughly
The powerful Pearson Test Prep practice test software, complete with hundreds of well-reviewed, exam-realistic questions, customization options, and detailed performance reports
40 performance-based exercises to help you prepare for the hands-on exam questions
A free copy of the CompTIA Network+ N10-008 Simulator Lite software, complete with meaningful lab exercises that enhance your hands-on skills
More than 60 minutes of video mentoring
A final preparation chapter that guides you through tools and resources to help you craft your review and test taking strategies
An Exam Essentials appendix that quickly recaps all major chapter topics for easy reference, both in print and interactive digital format
A key terms Glossary in both print and on the companion website, which acts as an interactive flash-card application
Study plan suggestions and templates to help you organize and optimize your study time
A 10% exam discount voucher (a $33+ value!)

Well regarded for its level of detail, study plans, assessment features, challenging review questions and exercises, video instruction, and hands-on labs, this approved study guide helps you master the concepts and techniques that ensure your exam success.

Master the topics on the CompTIA Network+ N10-008 exam, including:

Network topologies and media types
IP addressing
Network services
Data center architectures and cloud concepts
Routing, Ethernet switching, and wireless networking
Network availability and disaster recovery
Network security
Remote access
Network troubleshooting

Reader Paulo Cardoso says, "This is a great book. In addition, it comes with great additional resources."

Learn more about the CompTIA Network+ N10-008 Cert Guide at

Learn more at

More Network Troubleshooting and Support Articles:
• Introduction to Designing an IPv6 Address Plan
• Basics of RAID
• Steps For Designing a Crisis Management Plan
• What is Port Forwarding?
• How to Choose Work Area Network Cable Faceplate Locations
• Structured Network Troubleshooting Methodology Step 6 Verify Full System Functionality and, if Applicable, Implement Preventive Measures
• Why SFP Transceivers Stop Working and Their Possible Troubleshooting Guide
• Turning Names (URLs) Into IP Addresses
• How to Connect Two Computers Together with an Ethernet Cable
• Troubleshooting the Intermediate System to Intermediate System (IS-IS) Protocol