Chapter 7

Question 1

Shared medium is good for LAN. What are 2 reasons we do not use it for long distances.

Answer 1

1. Communication between machines will take more time

2. High bandwidth communication link between far places is very expensive.

Question 2

What network type is used for far off places

Answer 2

point-to-point network

Question 3

What is locality of reference principle

Answer 3

It has 2 parts

1. Computer likely to talk with the computer which is around it. This concept is also known spatial locality of reference
2. Computer communicates repeatedly with the same computer they did communicate once. This concept also known as temporal locality of reference.

Question 4

What are 3 most popular LAN topologies

Answer 4

1. Star
2. Ring
3. Bus

Question 5

What is star topology

Answer 5

It is called star because all computers are connected to a center point.

Question 6

What is hub

Answer 6

Center point of a network. It transfers packets from sender to receiver.

Question 7

What is difference between logical and physical star

Answer 7

Logical star means it is not necessary that all computers physically located in the form of star around hub.

Question 8

What is ring topology

Answer 8

All computers connected to each other in a ring manner. One computer is connected to second and second connected to 3rd and so forth.

Question 9

Does ring topology also have physical and logical concept

Answer 9

Yes

Question 10

What is bus topology

Answer 10

There is a single cable and all computers are connected to it. When we send information on that cable, all computer connected to that shared cable receives the information.

Question 11

Etherent use which topology

Answer 11

Bus topology

Question 12

What is segment in ethernet

Answer 12

One chunk of ethernet is called segment. Its maximum length is 500 meters. and computers on that segment must be separated by 3 meters distance.

Question 13

What is manchester encoding

Answer 13

It is used in Ethernet. The bit transmission in 2 levels. 1 and 0

Question 14

What is central mechanism for ethernet

Answer 14

CSMA/CD (Carrier sense multiple access with collision detection). It works like each computer first sense before sending signal on network either there any carrier/electrical signal on line. If it is then that computer hold for some time and try again after some period.