101 · Question #515
Which protocol data unit (PDU) is associated with the OSI model's Transport layer?
The correct answer is A. Segment. The Transport layer (Layer 4) of the OSI model uses Segments as its protocol data unit, encapsulating data for reliable or unreliable end-to-end delivery.
Question
Which protocol data unit (PDU) is associated with the OSI model's Transport layer?
Options
- ASegment
- BDatagram
- CPacket
- DBit
How the community answered
(27 responses)- A93% (25)
- B4% (1)
- D4% (1)
Why each option
The Transport layer (Layer 4) of the OSI model uses Segments as its protocol data unit, encapsulating data for reliable or unreliable end-to-end delivery.
At Layer 4, TCP and UDP both operate on Segments as the named PDU. The Transport layer is responsible for end-to-end communication, flow control, and segmentation of data from upper layers, and the unit of data at this layer is formally called a segment.
Datagram is the PDU associated with the Network layer (Layer 3), specifically used in connectionless protocols like UDP when referring to IP datagrams.
Packet is the PDU for the Network layer (Layer 3), where IP addresses are added and routing decisions are made.
Bit is the PDU for the Physical layer (Layer 1), representing the raw electrical or optical signals transmitted over a medium.
Concept tested: OSI model Transport layer PDU identification
Source: https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13769-5.html
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