An honest, complete introduction to the seven layer Open Systems Interconnection (OSI) model: what each layer actually does, how the model compares to the Transmission Control Protocol and Internet Protocol (TCP/IP) suite that real networks run, and how to read a packet capture and triage a symptom to the correct layer. The course is explicit about where the clean seven layer picture breaks down, including Transport Layer Security and tunnelling, and closes with a worked triage method you can apply to any future network or security symptom.
Nothing. Every course, exam, and certificate on the catalog is free — including retakes. All you need is a free Safeguard account.
None. The flagship course, Safeguard Certified Practitioner, is a beginner-level course — basic familiarity with how software is built helps, but every exam question is answerable from the lessons themselves.
You can retake it after a 24-hour cooldown, as many times as you need. Retakes are free, and each attempt draws a fresh random set of questions.
The Safeguard Certified Practitioner credential is valid for 24 months from issue. The expiry date is printed on the certificate and shown live on its public verification page. Renewing means passing the current exam again.
