Networks continue to add services as time goes on, and each additional service introduces more variables in network implementation. This also adds to the complexity of troubleshooting the network. Therefore, organizations increasingly depend on network administrators and network engineers with strong troubleshooting skills.

Engineers spend a large portion of their time troubleshooting. Therefore, all procedural tools that can be used to simplify the process are important. The time it takes to become familiar with each procedural tool may reduce the time spent troubleshooting in the field. The decision to invest time into learning a new procedure is not an easy choice to make. The main goal is to optimize the time spent learning new procedures to help shorten the time spent working in the field.

After the protocols and product lines have been considered, troubleshooting is essentially an exercise in logic .  When approaching a network problem, some type of problem-solving model should be used. This model should provide a logical step-by-step method of working toward a solution. It is important to realize that network engineers do not rely on a handbook of troubleshooting methodology when they encounter a problem. Instead, they work from their own personal skill sets and with the troubleshooting methodology that they have developed over time. A logical methodology can help minimize wasted time associated with unstructured troubleshooting.

Deductive reasoning works from the more general to the more specific .  This is informally referred to as a top-down approach. Deductive reasoning begins with developing a theory about the problem. That theory is then reduced to a specific hypothesis that can be tested. Observations are then collected based on the hypotheses. This allows the hypothesis to be tested with specific data. This will result in a confirmation or rejection of the original theory.

Inductive reasoning works the opposite way, moving from specific observations to broader generalizations and theories .  This is sometimes referred to as a bottom-up approach. Inductive reasoning begins with specific observations and measures. Patterns and regularities then lead to the formulation of tentative hypotheses that can be explored. Finally, some general conclusions or theories can be developed.
 

Web Links Reasoning http://trochim.human.cornell.edu/kb/dedind.htm