101 · Question #557

101 Question #557: Real Exam Question with Answer & Explanation

The correct answer is B: Packet. The OSI Network layer (Layer 3) uses the packet as its protocol data unit, which carries logical source and destination addresses used for routing between networks.

Question

Which protocol data unit (PDU) is associated with the OSI model Network layer?

Options

AFrame
BPacket
CSegment
DBit

Explanation

The OSI Network layer (Layer 3) uses the packet as its protocol data unit, which carries logical source and destination addresses used for routing between networks.

Common mistakes.

A. A frame is the PDU of the OSI Data Link layer (Layer 2), used for node-to-node delivery within the same network segment, not for inter-network routing.
C. A segment is the PDU of the OSI Transport layer (Layer 4), used by protocols such as TCP to provide end-to-end communication with sequencing and flow control.
D. A bit is the PDU of the OSI Physical layer (Layer 1), representing the raw electrical, optical, or radio signals transmitted over a physical medium.

Concept tested. OSI model Layer 3 protocol data unit identification

Reference. https://www.cisco.com/c/en/us/support/docs/ibm-technologies/logical-link-control-llc/10051-17.html

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