1-5 ENCAPSULATION AND DECAPSULATION

Question 1

What is encapsulation in the context of the OSI model?

Answer 1

Involves wrapping data with protocol information as it descends OSI layers.

Question 2

What occurs during the decapsulation process?

Answer 2

Data ascends OSI layers in the receiving device and each layer removes its corresponding header or footer.

Question 3

What does each OSI layer add during encapsulation?

Answer 3

A header or footer with specific control information.

Question 4

What is the purpose of encapsulation?

Answer 4

Ensures correct data interpretation and handling across network systems.

Question 5

What is the role of the Application Layer in encapsulation?

Answer 5

Encapsulates data with application-specific protocols like HTTP, SMTP, or FTP.

Question 6

What information does the Presentation Layer add during encapsulation?

Answer 6

Format and encryption information, ensuring data can be correctly interpreted.

Question 7

What is included in the Session Layer during encapsulation?

Answer 7

Control tokens and synchronization data, managing dialogue between systems.

Question 8

What does the Transport Layer introduce in the encapsulation process?

Answer 8

Segments or datagrams, adding source and destination port numbers for communication endpoints.

Question 9

What happens at the Network Layer during encapsulation?

Answer 9

Encapsulates into packets, adding logical addressing information with IP headers for routing.

Question 10

What is the function of the Data Link Layer in encapsulation?

Answer 10

Frames the packet, adding MAC addresses and error-checking information like CRC.

Question 11

What does the Physical Layer do in the encapsulation process?

Answer 11

Converts frames into electrical, radio, or optical signals for transmission over physical media.

Question 12

What are Service Data Units (SDUs)?

Answer 12

Data passed from a higher layer to a lower layer, considered the payload for transmission.

Question 13

Give an example of an SDU in the Application Layer.

Answer 13

A user’s text message in an instant messaging application.

Question 14

What is a Protocol Data Unit (PDU)?

Answer 14

Formed when each layer encapsulates the SDU by adding its specific header or footer.

Question 15

Provide an example of a PDU in the Application Layer.

Answer 15

The text message with HTTP headers if being sent via a web service.

Question 16

What does the encapsulation process convert SDUs into?

Answer 16

PDUs, adding layer-specific control information as the data descends through OSI layers.

Question 17

What happens during the decapsulation process?

Answer 17

Strips off headers or footers from PDUs, converting them back into SDUs as data ascends through OSI layers.