Stage 1 · Lesson 7 of 7
Debugging "it cannot connect"
Most cloud problems reach you as "it cannot connect", and the fix comes from checking layers in order. Does the name resolve (dig)? Is anything listening on the on the server (ss -tlnp)?
Can you reach the port from where the request starts (curl or nc)? Is a firewall, or route in the way? Is the app itself returning an error (curl -v, logs)?
Work from the bottom up and change one thing at a time, noting what you tried. This habit will save you hours in every later stage.
Common trapopening every port and giving everything a until it works, then never finding out which change fixed it.
A question to check yourself, an AI practice session and 3 cheat sheet entries come with the full roadmap. Unlock
Resources for this stage
Start with· follow one of these
- CourseFreeLinux Upskill Challenge
Linux Upskill Challenge · Beginner
Free, one task a day on a real cloud server: the shell skills this roadmap assumes
- VideoFreeComputer Networking: A Top-Down Approach (Video Lectures)
Jim Kurose and Keith Ross · Intermediate
Free lectures: watch the chapters on the application, transport and network layers for IP, TCP, UDP and DNS