Objective & prerequisites
Use a layered troubleshooting explanation without probing live systems. Prerequisites: basic Python expressions and files; use a disposable local practice folder and fictional data. This shared workshop complements the existing data/AI tracks and does not create a second progress system.
Understand the concept
DNS maps a host name to addressing information. TCP establishes a connection; TLS adds authenticated encryption; HTTP carries requests and responses. A DNS failure, timeout, TLS error and HTTP403 are different observations. An HTTP response means the request reached an application path, but it does not establish that the requested operation was authorized or completed. SSH is a separate authenticated remote-management protocol.
Worked example
Consider four fictional reports: name cannot resolve; connection timed out; certificate validation failed; HTTP403. Respectively inspect the name/configuration, connection path/availability, certificate identity/trust and application permission. Do not disable TLS verification to bypass the problem.
Try it yourself
Write a four-row troubleshooting table with observation, next authorized check and evidence needed. Use only these fictional messages; no scans, credential changes or production probes are part of the exercise. Record your prediction before running the supplied reference, then compare the observed result and explain any difference.
Worked solution
A403 does not justify retrying with guessed accounts. A TLS validation failure needs operator investigation of host/certificate, not turning verification off. A timeout can arise at several layers and needs bounded evidence rather than a confident diagnosis.
Knowledge check
Is HTTP403 equivalent to DNS failure? Try answering without rereading the example.
Check and explain
No.403 is an application-level response; DNS resolution failure occurs before an HTTP response is available.
Mini-project, mistakes & handover
Produce a short README with the question, exact local command, input meaning, checks and actual results. Include one failure case and its explanation. Never silently turn an exception into a passing result. Mark simulated behavior explicitly, credit the supplied teaching code and identify your own contribution. These activities are unsaved self-practice, not certification.
Authoritative reference
— consulted for the underlying interface/concept. The lesson and fictional examples are original teaching material. Python reference tested with 3.12; designed for 3.10+. Git lab requires Git 2.28+.
Try the activity before reading its reference. Keep your sources, commands and assumptions with your work. Companion activities are unsaved self-practice and do not award a certificate or change lesson progress.