48. What are the responsibilities of Network Layer?
Answer: The Network Layer is responsible for the source-to-destination delivery of packet possibly across multiple networks (links).
a. Logical Addressing
49. What are the responsibilities of Session Layer?
Answer: The Session layer is the network dialog Controller. It establishes, maintains and synchronizes the interaction between the communicating systems.
a. Dialog control
50. What are the responsibilities of Presentation Layer?
Answer: The Presentation layer is concerned with the syntax and semantics of the information exchanged between two systems.
51. What are the responsibilities of Application Layer?
Answer: The Application Layer enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as e-mail, shared database management and other types of distributed information services.
a. Network virtual Terminal
b. File transfer, access, and Management (FTAM)
c. Mail services
d. Directory Services
52. What are the frame format for data link layer?
Answer: The frame format for data link layer are:
– Header, payload filled, the trailer is the main parts of a frame.
– The header contains the number of characters in a frame & source and destination address.
– Payload filled contains the data to be sent.
– The trailer is the end of the packet and it also contains the starting and ending bits.
– This frame is sent to network layer.
53. How is Straight-through UTP cable built?
Answer: In Straight, through UTP cable all pins are matched on both sides. Pin-1 connects with Pin-1; Pin2 connects Pin2, this way each pin connects with the same number of the pin on another side.
54. Where do we use Straight-through UTP cable?
Answer: The straight-through cable is used to connect the following: –
- Hub / Switch to System
- Hub / Switch to Router
- Hub / Switch to Server
55. Why we cannot use Straight-through UTP cable to connect two systems directly?
Answer: In straight-through cable the pins which send data from one computer connected to the pins which also send data on other computers.
Simple a computer will not be able to pick the data from sending pins. So the transmission will be failed if we directly connect the two systems through the Straight-through UTP cable. To connect two systems directly we have to use the crossover cable which connects sending pins with receiving pins.
56. How is Cross-over cable built? Where do we use Cross-over cable?
Answer: In Cross-over cable the pins which send data from one end connected to the pins which receive data on another end. Pin1 connects with Pin3 while Pin2 connects with Pin6.
The Cross-over cable is used to connect the following: –
- Hub/Switch to Hub/Switch
- System to System
- Router to Router
- Router to System
57. Why acknowledged service is better?
Answer: Acknowledged service is better because:
– When data is sent acknowledgment at the reception of data occurs.
– If the frame is lost, then an error is detected and the data is sent again.
– Recovery of data takes place easily.
– It works for reliable channels where the error is minimum.
– This is a time-saving method and better than unacknowledged service.