GATE CSE 2004 | Question: 15

Question

Choose the best matching between $\text{Group 1}$ and $\text{Group 2}$

$$\begin{array}{|l|l|}\hline \textbf{Group-1} & \textbf{Group-2} \\\hline  \text{P. Data link layer} & \text{1. Ensures reliable transport of data over a physical point-}\\ & \text{to-point link} \\\hline   \text{Q. Network layer} & \text{2. Encodes/decodes data for physical transmission} \\\hline  \text{R. Transport layer} & \text{3. Allows end-to-end communication between two }\\ & \text{processes} \\\hline \text{} & \text{4. Routes data from one network node to the next} \\\hline \end{array}$$

• A. $\text{P-1, Q-4, R-3}$
• B. $\text{P-2, Q-4, R-1}$
• C. $\text{P-2, Q-3, R-1}$
• D. $\text{P-1, Q-3, R-2}$

Comments

@ayushsomani

yes, Encoding and Decoding data for physical transmission is done by physical layer using manchester or differential manchester encoding

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References : https://en.wikipedia.org/wiki/Point-to-Point_Protocol

 

 

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References : Forouzan 

For Encode & Decode ..

Converting binary data  into electrical, or electromagnetic signals (encoding) and converting them back (decoding) is the primary function of the Physical Layer, not any of the upper layers.

Answer 1

Answer is A.

Comments

But I have read somwhere that Data Link Layer encodes/decides data for physical transmission. So P should be matched with  2 in this case.

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See here:

https://en.wikipedia.org/wiki/Physical_layer

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Sir please suggest me one good book for networking. I can't do well in gate..or tell me how to prepare well.

Answer 2

Option A:

Explanation::

Data Link Layer :: Hop to Hop connection or point to point connection.

Transport Layer:: Service point addressing/Socket to socket connection or end to end connection with full reliability.

Network Layer:: Host to Host

Comments

not right person within the house to right person within house

means?

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not right person within the house to right person within house  ??

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Paras Nath

Transport Layer:: Service point addressing/Socket to socket connection or end to end connection with full reliability.

 what about UDP ? (it is not reliable)

Answer 3

Answer: A. P-1, Q-4, R-3, Physical layer- encodes/decodes data for physical transmission using manchester and differential manchester encoding technique.

Answer 4

Encoding and Decoding means at which layer it's done

Presentation layer

Comments

Physical layer dude

Answer 5

..

Answer 6

data link layer does encode and decode for physical transmission so ...b is the answer

Comments

See here:

https://en.wikipedia.org/wiki/Physical_layer

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FUNCTIONS OF TRANSPORT LAYER :

Segmentation and Reassembling : A message is divided into segments; each segment contains sequence number, which enables this layer in reassembling the message. Message is reassembled correctly upon arrival at the destination and replaces packets which were lost in transmission.
Connection Control : It includes 2 types :
Connectionless Transport Layer : Each segment is considered as an independent packet and delivered to the transport layer at the destination machine.
Connection Oriented Transport Layer : Before delivering packets, connection is made with transport layer at the destination machine.
Flow Control : In this layer, flow control is performed end to end.
Error Control : Error Control is performed end to end in this layer to ensure that the complete message arrives at the receiving transport layer without any error. Error Correction is done through retransmission.

FUNCTIONS OF DATA LINK LAYER :

Framing: Frames are the streams of bits received from the network layer into manageable data units. This division of stream of bits is done by Data Link Layer.
Physical Addressing: The Data Link layer adds a header to the frame in order to define physical address of the sender or receiver of the frame, if the frames are to be distributed to different systems on the network.
Flow Control: A flow control mechanism to avoid a fast transmitter from running a slow receiver by buffering the extra bit is provided by flow control. This prevents traffic jam at the receiver side.
Error Control: Error control is achieved by adding a trailer at the end of the frame. Duplication of frames are also prevented by using this mechanism. Data Link Layers adds mechanism to prevent duplication of frames.
Access Control: Protocols of this layer determine which of the devices has control over the link at any given time, when two or more devices are connected to the same link.

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flow and error  are in both the layers