CompTIA Network+ OSI Model Practice Questions: Protocols

8 free, exam-style CompTIA Network+ OSI Model (N10-009) practice questions covering Protocols. 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. Which of the answers listed below refers to a common OSI Layer 2 protocol?

Explanation: ARP (Address Resolution Protocol) resolves IP addresses to MAC addresses and operates at Layer 2/Layer 3 boundary, but is often considered a Layer 2 protocol as it works with frames.

Q2. Which OSI layer uses TCP and UDP port numbers?

Explanation: The Transport layer uses ports to identify application conversations.

Q3. At which OSI layer does flow control using TCP windowing occur?

Explanation: TCP windowing is a Layer 4 flow control mechanism.

Q4. Which OSI layer is responsible for end-to-end reliable delivery when TCP is used?

Explanation: TCP provides reliability, sequencing, and retransmission at the Transport layer.

Q5. Which OSI layer adds source and destination port numbers?

Explanation: TCP and UDP add port numbers at the Transport layer.

Q6. Which OSI layer is most associated with routing protocol decisions?

Explanation: Routing protocols support Layer 3 path selection and packet forwarding.

Q7. Which OSI layer is most associated with retransmission of lost TCP segments?

Explanation: TCP retransmission is a Transport layer reliability function.

Q8. Which OSI layer is most associated with ARP in IPv4 networks?

Explanation: ARP resolves Layer 3 IPv4 addresses to Layer 2 MAC addresses, bridging the Layer 2 and Layer 3 boundary.

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