Proxies, blocked ports and TLS inspection
Tell apart DNS failures, blocked ports, proxy problems and TLS/certificate issues, and know why browsers and background services can see different proxy settings.
- Level
- Intermediate
- Length
- About 45 minutes
- Contents
- 3 lessons · 1 video · final exam
- Status
- Published · updated 1 Oct 2026
Skills you'll practise
- Recognize the symptom pattern of DNS failure vs blocked port vs proxy vs TLS problem
- Read proxy settings for users (browser) and services (WinHTTP)
- Explain TLS inspection and why some apps fail with it
Course outline
- 1.Proxies, blocked ports and TLS inspectionVideo · 5 min
- 2.Four failures that look alikeLesson · 14 min
- 3.TLS inspectionLesson · 12 min
- 4.Asking for a firewall or inspection change with the right evidenceLesson · 12 min
- 5.Proxies, blocked ports and TLS inspection: knowledge checkKnowledge check · 17 questions
- 6.One website fails through the company proxyScenario
- 7.Final exam6 questions · passing it completes the course, so people who already know the material can test out
Sources it draws on
The lessons and questions are written from these references, so learners can go back to the original.
- Microsoft Learn: netsh winhttp commands
- Microsoft Learn: Proxy settings in Windows
- RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3
- Web Proxy Auto-Discovery and PAC files overview
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