TCP - Layer 4 Protocol for Network Communication

Which of the following protocols operates at Layer 4 of the OSI model?

A.

TCP

B.

ARP

C.

IMAP

D.

POP3

A.

The correct answer is A. TCP.

The OSI model is a conceptual framework that defines how data communication occurs between different networked devices. It consists of seven layers, each with a specific function. The layers are:

1. Physical layer: This layer is responsible for transmitting raw bits over a physical medium.
2. Data link layer: This layer is responsible for the reliable transmission of data frames between devices.
3. Network layer: This layer is responsible for routing and forwarding data between networks.
4. Transport layer: This layer is responsible for the reliable transmission of data between applications.
5. Session layer: This layer establishes, manages, and terminates sessions between applications.
6. Presentation layer: This layer translates data between the application layer and the lower layers of the OSI model.
7. Application layer: This layer provides services to end-user applications.

The Transport layer is Layer 4 of the OSI model, and its primary function is to provide reliable communication between applications running on different networked devices. The Transport layer accomplishes this by segmenting and reassembling data and providing error detection and correction.

TCP (Transmission Control Protocol) is a reliable transport protocol that operates at Layer 4 of the OSI model. TCP provides a connection-oriented communication service between applications, which means that before data transmission occurs, a connection is established between the sender and the receiver. TCP ensures that all data packets are delivered reliably and in the correct order.

ARP (Address Resolution Protocol) operates at Layer 2 of the OSI model and is responsible for mapping a network address (such as an IP address) to a physical address (such as a MAC address).

IMAP (Internet Message Access Protocol) and POP3 (Post Office Protocol version 3) both operate at Layer 7 of the OSI model and are used by email clients to retrieve email messages from mail servers.

In summary, TCP operates at Layer 4 of the OSI model, while ARP, IMAP, and POP3 operate at Layers 2 and 7.