Which OSI/ISO layers are TCP and UDP implemented at?

The correct answer is D. Transport layer. In the OSI model, TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are both implemented at Layer 4 - the Transport layer. The Transport layer is responsible for end-to-end communication, segmentation, flow control, and error recovery between hosts. TCP…

Submitted by katya_ua· Apr 18, 2026Network and Communications Security

Question

Which OSI/ISO layers are TCP and UDP implemented at?

Options

AApplication layer
BPresentation layer
CSession layer
DTransport layer

How the community answered

(39 responses)

B
8% (3)
C
3% (1)
D
90% (35)

Explanation

In the OSI model, TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are both implemented at Layer 4 - the Transport layer. The Transport layer is responsible for end-to-end communication, segmentation, flow control, and error recovery between hosts. TCP provides reliable, connection-oriented delivery with sequencing and acknowledgment; UDP provides faster, connectionless, best-effort delivery. The Application layer (L7) handles user-facing protocols like HTTP and FTP; the Presentation layer (L6) handles data formatting; the Session layer (L5) manages sessions between applications.

Topics

#OSI Model#TCP/IP#Transport Layer#Networking Protocols

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