ISA/IEC 62443 Cybersecurity Fundamentals Specialist — Question 40

What does Layer 1 of the ISO/OSI protocol stack provide?

Answer options

• A. Data encryption, routing, and end-to-end connectivity
• B. Framing, converting electrical signals to data, and error checking
• C. The electrical and physical specifications of the data connection
• D. User applications specific to network applications such as reading data registers in a PLC

Correct answer: C

Explanation

Layer 1 of the ISO/OSI model is responsible for the physical transmission of data, including the electrical and physical specifications of the data connection, making option C the correct answer. Options A, B, and D pertain to higher layers that deal with data handling, framing, and application specifics, which are not functions of Layer 1.