CompTIA Network+ OSI Model Practice Questions: PDUs

10 free, exam-style CompTIA Network+ OSI Model (N10-009) practice questions covering PDUs. Each question shows the correct answer and a clear explanation. Ready for the real thing? Take the full timed quiz below.

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Q1. In the OSI model, the protocol data unit at the Physical Layer is known as:

Explanation: At Layer 1 (Physical Layer), data is transmitted as raw bits.

Q2. In the OSI model, the Layer 4 UDP protocol data unit is called:

Explanation: For UDP, the PDU at Layer 4 (Transport) is typically referred to as a Datagram. (Note: TCP uses 'Segment').

Q3. In the OSI model, the Layer 2 protocol data unit is known as:

Explanation: The PDU at Layer 2 (Data Link) is the Frame.

Q4. In the OSI model, the Network Layer protocol data unit is called:

Explanation: The PDU at Layer 3 (Network) is the Packet.

Q5. In the OSI model, the Layer 4 TCP protocol data unit is referred to as:

Explanation: The PDU for TCP at Layer 4 is the Segment.

Q6. What is the PDU at the Transport layer commonly called?

Explanation: Transport layer data units are commonly called segments for TCP and datagrams for UDP.

Q7. What is the PDU at the Network layer commonly called?

Explanation: The Network layer encapsulates data into packets for logical addressing and routing.

Q8. What is the PDU at the Data Link layer called?

Explanation: The Data Link layer uses frames to carry data across a local link.

Q9. What is the PDU at the Physical layer?

Explanation: The Physical layer transmits raw bits as electrical, optical, or radio signals.

Q10. Which OSI layer encapsulates data into frames before physical transmission?

Explanation: The Data Link layer creates frames that are then transmitted as bits by the Physical layer.

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