Which scenario describes a function provided by the transport layer?
b. A student is playing a short web-based movie with sound. The move and sound are encoded within the transport layer header.
c . A student is using a classroom Volp phone to call heme. The unicue identifer bumed into the phone is a transport layer address used to contact another network device on the same nebwork.
d. A student has two web browser windows open in order to access two web stes. The transport layer ensures the correct web page is delivered to the correct browser window.
The Correct Answer and Explanation is :
The correct answer is:
d. A student has two web browser windows open in order to access two websites. The transport layer ensures the correct web page is delivered to the correct browser window.
Explanation:
The transport layer (Layer 4 in the OSI model) is responsible for providing end-to-end communication services for applications. Its key functions include:
- Segmentation and Reassembly: It breaks down data from higher layers (like HTTP) into smaller segments for transmission and reassembles them correctly at the destination.
- Flow Control: Ensures that the sending device does not overwhelm the receiving device with too much data too quickly.
- Error Handling: It checks for errors in data transmission and ensures reliable communication, often via protocols like TCP (Transmission Control Protocol).
- Multiplexing: It can manage multiple connections between devices, using port numbers to differentiate between different services or application processes running on a device.
In scenario d, the transport layer is ensuring that data meant for one application (e.g., a web page for browser window 1) doesn’t get mixed up with data for another application (e.g., a web page for browser window 2). It uses port numbers to distinguish between the two different browser windows. For example, if both windows are accessing different websites, the transport layer ensures that the data for each website is delivered to the correct browser window, keeping them separate and in the correct order. This is done using protocols like TCP and UDP, which provide a system for addressing and ensuring the integrity of the data.
Why other options are incorrect:
- b. A student is playing a short web-based movie with sound. The movie and sound are encoded within the transport layer header.
This statement is incorrect because the transport layer does not encode media such as movies and sound. The application layer handles the encoding and transmission of media files, while the transport layer ensures reliable communication between devices. - c. A student is using a classroom VoIP phone to call home. The unique identifier burned into the phone is a transport layer address used to contact another network device on the same network.
This is incorrect because the transport layer doesn’t use unique identifiers burned into devices (such as MAC addresses) for communication. These addresses belong to the data link layer (Layer 2), which is responsible for communication between devices on the same network. The transport layer uses IP addresses and port numbers to ensure communication between applications.