CompTIA Network+ Practice Test

In which OSI layer would you find TCP and UDP?

1. Data Link layer

2. Transport layer

3. Network layer

4. Session layer

The correct answer is: Transport layer

The correct answer is the Transport layer. This layer is responsible for providing end-to-end communication services for applications. It ensures that data is transferred reliably and in the correct sequence. TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two key protocols that operate at this layer. TCP is a connection-oriented protocol, meaning it establishes a connection before data transmission and ensures that all packets are received and in order, providing reliable communication. In contrast, UDP is a connectionless protocol that sends messages without establishing a connection, offering faster transmission with no guarantee of delivery or order, which can be suitable for applications like video streaming where speed is essential. Other layers mentioned, such as the Data Link layer, Network layer, and Session layer, serve different functions. The Data Link layer is concerned with node-to-node data transfer and error correction in local network areas. The Network layer deals with routing packets across networks, focusing on logical addressing and path determination. The Session layer manages sessions or connections between applications, controlling the dialogue between systems. Thus, TCP and UDP's role in providing communication services places them specifically within the Transport layer of the OSI model.