Q. Describe the various application of
Networking?
Ans:- There is a long list of application areas which can be benefited by
establishing networks few of the applications of computer networks are:-
· Information
retrieval systems which search for books, technical reports, papers and
articles on particular topics.
· News access
machines which can search past news, stories or abstracts with given search
criteria.
·
Airline
reservation, hotel-booking, railway reservation, car rental etc.
· A writer’s aid; A
dictionary, thesaurus, phrase generator, indexed dictionary of quotations etc.
· Stock market
information systems which allow searches for stocks that meet certain criteria,
performance comparisons, moving averages, and various forecasting techniques.
·
Electronic
financial transactions (FFT) between banks and via cheque clearing house.
·
Electronic mail
messages systems (EMMS).
· Corporate
information systems such as marketing information system, customer information
system, product information system, personnel information system etc.
· Corporate systems
of different systems such as order-entry system, centralized purchasing,
distributed inventory control etc.
·
On-line systems
for investment advice and management, tax minimization etc.
·
Resources of
interest to a home user.
·
Sports results.
·
Theater, movies
and community events information.
·
Shopping
information, prices, advertisements.
·
Restaurants, good
food guide.
·
Household
magazine, book reviews, film reviews etc.
·
Holidays, hotels,
travel booking.
·
Radio & TV
programs.
·
Medical
assistance service.
·
Insurance
information
·
Transmission
channel
·
Network Interface
Unit (NIU)
·
Servers
·
Workstations
Q. Write a Short note on the following.
i. Analog and Digital Signal
ii. Bandwidth
Ans:-
Analog and Digital Signals:- Like the data they represent, signals can be
either analog or digital. An analog
signal has infinitely many levels of intensity over a period of time. As the waves moves from value A to value
B. It passes through and includes an
Infinite number of values along its path.
A digital signal, on the other hand, can have only a limited number of
defined values. Although each value can
be any number, it is often as simple as 1 and 0.
Program:-
Comparison of Analog and Digital signals.
Bandwidth:-
Difference between the maximum and minimum frequency of a frequency
spectrum of the signal is known as bandwidth of the signal.
Here the term frequency spectrum of a signal means the
set of all frequencies that constitutes it.
A simple signal has only a single frequency, However a complex signal
can be broken down into simple signals having different frequencies. The set of these frequencies are known as
spectrum of the signal.
In other words, we can say that the difference between
the highest frequency and the lowest frequency is known as bandwidth. To calculate the bandwidth, Subtract the
lowest frequency from the highest frequency of the range.
Frequency:- The
frequency is the rate at which the signal repeats.
Q. Write a short note on the following.
i. Packet Transmission
ii. Long Distance Communication
Ans:- Packet Transmission:-
In a packet transmission, data are transmitted in discrete units of
potentially variable. Variable length
blocks called packet is established by the network. Longer transmission are broken up into
multiple packets each packets contains not only data but also a header with
control information (such as priority codes and source and destination
addresses). The packets are sent over
node to node.
Two popular approaches of packet switching:-
·
Datagram approach
·
Virtual circuit
approach
Datagram Approach:-
In Datagram approach, To packet transmission, each packet is treated
independently from all others. Even when
one packet represents just a piece of multi packet transmission, the network
treats it as though it existed alone.
Packets in this technology are referred to as datagrams.
This approach can cause the datagrams of a
transmission of a transmission to arrive at their destination out of order.
Virtual Circuit Approach:- In the virtual circuit approach to packet
transmission, the relationship between all the packets belonging to a
message. A single route is chooses
between sender and receiver at the beginning of the session. When the data are sent, all the packets of
the transmission one after another along that route.
Virtual circuit transmission is implemented in two
formats:-
·
SVC (Switch
Virtual Circuit)
·
PVC (Permanent
Virtual Circuit)
SVC:- In this
method, a virtual circuit is created whenever it is needed. For example- Imagine that station A wants to
send four packets to station X. First, A
requests the establishment of a connection to X. Once the connection is in place, the packets
are sent one after another and is sequential order. Only one single rate exists for the duration
of transmission.
Each time that A wishes to communicate with X, a new
route is established. The route, many be
the same each time or it may differ in response to varying network conditions.
PVC (Permanent Virtual Circuit):- Permanent Virtual Circuits are comparable to
leased lines in circuit switching. In
this method the same virtual circuit is provided between two users on a
continuous basis. The circuit is
dedicated to the specific users. No one
else can use it and, because it is always in place. It can be used without connection establishment
and connection termination. Where as two SVC users may get a different route
every time they request a connection, Two PVC users always get the same route.
Q. Explain the concepts of database with its
relevant advantages and disadvantages. What are the characteristics of an ideal database?
Ans:-
Database:- A
database is a collection of related information stored so that it is available
to many uses for different purposes. The
content of a database is obtained by combining data from all the different
sources in an organization. Database
play a critical role in almost all areas where computers are used, including
business, law, engineering, medicine, education, library science etc.
The management of data in database system is done by
means of a general purpose S/W package called a database management
system. The database management system
is the major S/W component of a database system. Some commercially available DBMS are INGRES,
ORACLE, SYBASE.
The role of the DBMS as an intermediate between the
users and the database is very much like the function of a salesperson in a
consumers distributor system. A consumer
specified desired items by filling out an order from which is submitted to a
salesperson at the counter. The
salesperson present the specified items to consumer after they have been
retrieved from the storage room.
Similarly, the database use needs to know only what data he or she
requires; the DBMS will take care of retrieving it.
Definitions:-
Data:- Data can
be defined as a representation of facts, concepts or instruction in a
formalized manner suitable for communication or processing by human or
electronic machine. Data is represented
with the help of characters like Alphabets (a-z), digits (0-9) or special
characters (1, -, 1, *, <, >, = etc.)
Data Item:- A
set of character which are used together to represent a specific data
element. Example Name of a student in a
class is represented by the data item, say NAME.
Record:- Record
is a collection of related data items e.g- A payroll record for an employee
contains such data fields as name, age, qualification, sex, basic pay, DA, HRA,
PF etc.
File:- File is
a collection of related records stored in secondary storage that is available
for future use e.g- Payroll file might consist of the employee pay records for
a company.
Information:-
Information is classified data so that it has some meaningful values.
Data Processing:-
Data Processing means manipulating the data (raw data) to make it more useful. Data Manipulation consists of such operation
as classification, sorting & calculations etc.
Definition of Database:- A database is well organized collection of
data that are related in a meaningful way which can be accessed in different
logical orders but are stored only once.
In this definition, it is clear that data in a
database has the following features:-
·
It is well
organized.
·
It is related.
·
It is accessible
in different orders.
·
It is stored only
once.
Data Base System, Concept and Meaning:-
A database system consists of a collection of
interrelated data and a set of programs to access the data. Hence, database system is the DBMS S/W
together with the data itself. It is a
S/W that assists in maintaining and utilizing a database.
A Database Management System (DBMS) consists of –
·
A collection of
interrelated data. This part of DBMS is
usually referred to as the database.
·
A set of
application programs used to access, update and manage that data. This portion forms the Data Management
System.
The goal or purpose of a database system is to provide
an environment that is both convenient and efficient to use in.
·
Retrieving
information from the database, and
·
Storing
information into the database.
In other words, a DBMS allows you to store, update and
retrieve data hence making it easy to maintain and retrieve information from a
database.
Advantages of Database System:-
·
Minimal
Redundancy:- In file systems each
application has its own private files.
This can often lead to considerable redundancy in stored data, with
reinltant waste in storage space. For
example, A personnel application and an education-records application may each
own a file containing department information for employees. These two files can be integrated, and the
redundancy eliminated, if the DBA is aware of the data requirements for both
applications.
·
Sharing of
Data:- It means not only that existing
applications can share the data in the database, but also that new applications
can be developed to operate against that same stored data. In other words, the data requirements of new
applications may be satisfied without having to create any new stored files.
·
Standards can be
enforced:- With central control of the
database, the DBA can ensure that all applicable standards are followed in the
representation of the data such as format of data items, documentation
standards etc. Which will result in
uniformity of the entire database as well as its usage.
·
Search
Capability:- The user of a database may
ask wide variety of the questions about the data if a quick answer is needed at
a terminal the search will have to be fast the capability to search a database
quickly. An objective of database
organization, then, may be achieve fast flexible search capability.
·
Integrity:- By integrity we mean unification of several
files into one file. When a database
contains data employed by many different users it is important that the data
items & associations between data items not be destroyed. Hardware failures various types of accidents will occur
occasionally. The storage of data its updating & insertion procedures, must
be such that the system can recover from these circumstances without harm to
the data. This integration eliminates
inconsistency.
·
Privacy &
Security:- Data in database systems must
be kept secure & private. Data
security refers to protection of data against accidental or intentional
disclosure to unauthorized persons or unauthorized modifications.
·
The Interface
with the past:- Organizations which have
been using data processing for some time having a major investment in their
existing programs, procedures and data.
When an organization installs new data-base S/W it is important that it
can work with the existing programs & procedures and that the existing data
can be converted.
·
Data
Migration:- Some data are referenced
very frequently and others only occasionally.
It is desirable to store the frequently reference data in such a manner
that they can be accessed quickly
conveniently. The rarely accessed
data can be stored in a cheaper fashion.
The rarely accessed data can be stored on magnetic tape & frequently
accessed data may be on disk or drum.
The
process of adjusting the storage of data is called data migration.
·
Faster
development of new application:- When a
new application is proposed, it is likely that the data required is already
stored in the database. Therefore,
development time is reduced as no file creation phase is required for the new
application.
·
More control over
concurrency:- In a file system, if two
users permitted to access the data simultaneously or both attempt to perform
updates, they will interfere, with each other and one might overwrite the value
recorded by the other. A DBMS has
subsystems to control concurrency so that transaction are not lost or performed
incorrectly.
Disadvantages of Database System:-
·
High Cost of
DBMS:- Because a complete DBMS is very
large and sophisticated piece of S/W, it is expensive to purchase.
·
High Hardware
Cost:- Additional memory and processing
power may be required to run the DBMS, resulting in the need to upgrade the
H/W.
·
High Programming
Cost:- Because a DBMS is a complex tool
with many features, it requires experienced programmers resulting in extra
payment for their heir and expertise.
·
Complex:- Another major disadvantages is that database
processing tends to complex, large amounts of data in many different formats
can be interrelated in the database.
·
Backup &
Recovery are more difficult:-
Determining the exact state of the database at the time of failure may
be a problem. It may be even more
difficult to determine what should be done next.
Even
the failure of just one application program may pose serious problems.
·
Confidentiality,
Privacy and Security:- When information
is centralized and is made available to users from remote locations, the
possibilities of abuse are often more that in conventional data processing
system.
Characteristics of an Ideal Database:- A database represent some aspect of the real
world, sometimes called the mini world or the Universe of Discourse (U.D.). In, general, an ideal database should
provide the following facilities:-
a. Creation of a file, addition to data, deletion of
data, creation, addition and deletion of entire file.
b. Retrieving data collectively or selectively.
c. Sorting and indexing of data.
d. Reports generation facilities.
e. Mathematical functions can be performed on the data to
fetch the desired calculation.
f. To maintain the data integrity.
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