Introduction The last time we looked at how to diagnose like a doctor, we focused on the differential diagnosis (dDx). This is the mental model that doctors use to assess possible causes of an issue and prioritize tests to figure out what’s happening. For more information on differential diagnosis, you can read Part 1 of this series. Today, we need to talk through how we gather the best information to feed your dDx and how to make your diagnostic actions count.

Introduction The IT field is terrible at teaching people how to troubleshoot. Sure, if you got a CompTIA A+ or a CCNA, there were modules that talked about how to solve problems, but how much time did you actually spend on those modules? The CCNA course I took spent all of 5 minutes on it, with the message “there’s probably going to be a question that will ask what order these steps come in.