OSI Model — Set 3
Computers · OSI मॉडल · Questions 21–30 of 70
Which organization developed the OSI model for network standardization?
Correct Answer: D. ISO
The International Organization for Standardization (ISO) introduced the OSI model in 1984. It was created to provide a vendor-neutral framework for different computer systems to communicate. Although the TCP/IP model is more widely used, the OSI model remains the standard for teaching network theory.
The 'Trailer' field in a data unit is uniquely found at which layer of the OSI model?
Correct Answer: A. Data Link Layer
Only the Data Link Layer adds a trailer to its data unit (the frame) to facilitate error detection. Higher layers only add headers to the data received from the layer above. This trailer typically contains the Frame Check Sequence (FCS) used by the receiver to verify data integrity.
Which layer of the OSI model manages the 'Half-Duplex' and 'Full-Duplex' communication modes?
Correct Answer: C. Session Layer
The Session Layer is responsible for controlling the dialogue between two systems. It determines whose turn it is to transmit and manages the flow of the conversation. This ensures that the two applications can exchange data in an orderly fashion without conflict.
At which layer of the OSI model does a 'Repeater' or 'Hub' function?
Correct Answer: A. Layer 1
Repeaters and hubs operate at the Physical Layer (Layer 1) because they deal purely with electrical signals. They do not look at MAC or IP addresses and simply amplify or broadcast the signal to all ports. These devices are less 'intelligent' than switches or routers.
Which layer is responsible for compressing data to reduce the number of bits that need to be transmitted?
Correct Answer: D. Presentation Layer
Data compression is a key task of the Presentation Layer to improve network efficiency. By reducing the size of the data, this layer helps in faster transmission and lower bandwidth usage. It essentially optimizes the payload before it is sent further down the protocol stack.
The 'Media Access Control' (MAC) sublayer is a part of which OSI layer?
Correct Answer: A. Data Link Layer
The Data Link Layer is divided into the Logical Link Control (LLC) and the Media Access Control (MAC) sublayers. The MAC sublayer determines how a device gains access to the physical transmission medium. It is the part of the layer that interacts most closely with the Physical Layer hardware.
Which layer uses 'Port Numbers' to identify specific processes or applications?
Correct Answer: C. Transport Layer
The Transport Layer uses port numbers to ensure that data is delivered to the correct application on a host. For example, HTTP uses port 80 and HTTPS uses port 443. Port numbers allow multiple applications to share a single network connection simultaneously.
Which layer of the OSI model is considered the 'User Support' layer?
Correct Answer: D. Layers 5, 6, and 7
The Session, Presentation, and Application layers are often grouped as user support layers. They deal with the software aspects and the interface with the user. In contrast, the Physical, Data Link, and Network layers are known as network support layers.
Multiplexing and De-multiplexing are functions primarily handled at which layer?
Correct Answer: A. Transport Layer
The Transport Layer handles multiplexing, which allows multiple applications to send data over the same network path. At the receiving end, it performs de-multiplexing to route each segment to its intended application based on port numbers. This is a crucial feature for modern multi-tasking operating systems.
What is the standard name for a data unit at the Network Layer?
Correct Answer: C. Packet
The data unit at the Network Layer is called a 'Packet' (often specifically an IP packet). In the Data Link Layer, it is called a Frame, and in the Transport Layer, it is called a Segment. This terminology helps technicians identify exactly which layer of communication is being discussed.