Which PDU format is used when bits are received from the network medium by the NIC of a host?
a) file
b) frame
c) packet
d) segment
Correct Answer: b
When data is transmitted over a network, it is divided into smaller, manageable units for efficient transmission and reception. These units are organized into different layers of the network protocol stack, and each layer adds its own header and possibly footer information to create a specific Protocol Data Unit (PDU).
The PDU format used when bits are received from the network medium by the Network Interface Card (NIC) of a host is a “frame.”
Correct Answer (b – Frame):
When data is transmitted over a network, it is initially broken down into frames at the data link layer (Layer 2 of the OSI model). A frame is the smallest unit of data that is transmitted over a network and is composed of a header and a trailer along with the actual data payload.
The header contains essential information such as source and destination MAC addresses, frame type, and error-checking information like a CRC (Cyclic Redundancy Check) to ensure data integrity.
The trailer may contain additional error-checking information or padding to ensure that the frame meets the minimum length requirement.
The frame is the PDU used at the data link layer, and it serves as the envelope for the data being transmitted. When the NIC of a host receives bits from the network medium, it interprets them as frames, extracts the necessary information from the frame header, and passes the data payload to the higher layers of the OSI model for further processing.
This process allows the data to be correctly delivered to the intended application or service running on the host.
Now, let’s explain why the other options (a – File, c – Packet, and d – Segment) are not correct:
a) File:
A “file” is not a PDU format used in network communication. Files are collections of data stored on storage devices like hard drives or in the cloud. They are not relevant to the process of transmitting data over a network.
Files are broken down into smaller units like packets when they are sent over a network, but these smaller units are not referred to as “files.” Therefore, “file” is not the correct answer.
c) Packet:
“Packets” are a PDU format used at a higher layer of the OSI model, specifically the network layer (Layer 3). When data is transmitted across a network, it is divided into packets at this layer. Packets contain information such as source and destination IP addresses, as well as protocol information.
While packets are essential for routing data between different networks and subnets, they are encapsulated within frames at the data link layer for transmission over the local network segment.
So, “packet” is not the correct answer because it is not the PDU format used when bits are received directly from the network medium by the NIC.
d) Segment:
“Segments” are used at the transport layer (Layer 4) of the OSI model. Segments are created by the transport layer protocol (e.g., TCP or UDP) and include information such as source and destination port numbers, sequence numbers, and error-checking information.
However, segments are not the PDU format used when bits are received by the NIC from the network medium. Instead, segments are further encapsulated into packets and then into frames before being transmitted over the network. Therefore, “segment” is not the correct answer.
In summary, when bits are received from the network medium by the NIC of a host, the PDU format used is a “frame.” Frames are essential for local network communication and contain the necessary information for delivering data to the correct destination within the same network segment.
Other PDU formats like packets and segments are used at higher layers of the OSI model and are encapsulated within frames before being transmitted over the network. “File” is not a PDU format used in networking; it refers to collections of data stored on storage devices.
MBA,BBA.
I am Smirti Bam, an enthusiastic edu blogger with a passion for sharing insights into the dynamic world of business and management through this website.
I hold a MBA degree from Presidential Business School, Kathmandu, and a BBA degree with a specialization in Finance from Apex College,
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