BPSC Assistant Network Engineer (ANE) Exam 2020 Question Full Solution
1.
(i) Congestion Control কী?
কী কী ভাবে
Congestion Control করা যায়?
Answer:
Congestion is nothing but a situation in network layer due to heavy massage traffic
that slows down the network response time. Techniques used to control or
prevent this type of situation refer to Congestion control. Congestion control
techniques can be broadly classified into two categories:
I.
Open Loop Congestion Control
II. Closed Loop Congestion Control
Open
Loop Congestion Control:
These
policies are adopted to prevent congestion before it happens in the network, Congestion can be handled either by the source or the destination.
Policies adopted by open loop congestion control are:
Retransmission
Policy
Window
Policy
Discarding
Policy
Acknowledgment
Policy
Admission
Policy
Closed
Loop Congestion Control:
These
policies are used to reduce congestion after it happens. Several techniques are
used by different protocols, some of them are:
Backpressure
Choke
Packet Technique
Implicit
Signaling
Explicit
Signaling
Forward
Signaling
Backward
Signaling
(ii)
HTMLও CSS কী ?
Answer:
HTML stands for “Hypertext Markup Language". Hypertext refers to the
hyperlinks that an HTML page may contain and Markup language refers to the way
tags are used to define the page layout and elements within the page. So HTML
is the standard markup language for documents designed to be displayed in a web
browser. It can be assisted by technologies such as Cascading Style Sheets and
scripting languages such as JavaScript.
HTML
elements are represented by<> tags.
On
the other hand, CSS stands for Cascading Style Sheets. It describes how HTML
elements are to be displayed on screen, paper, or in other media. Using CSS,
one can control the color of the text, the style of fonts, the spacing between
paragraphs, how columns are sized and laid out, what background images or
colors are used, layout designs and variations in display for different devices
and screen sizes as well as a variety of other effects. CSS saves a lot of work.
It can control the layout of multiple web pages all at once. There are three
ways we can implement CSS: internal, external, and inline styles. External
style sheets are stored in CSS files.
2.
(i) Optical disk কীভাবে
data Read/Write করে বর্ণনা করুন।
Answer:
Optical
disk: is an
electronic data storage medium that can be written to and read from using a
low-powered laser beam. In later optical disc systems, a laser read the dots
and the data is converted to an electrical signal. Then the data is converted
to audio or visual output.
Write
onto an Optical Disc
The
tiny marks made in the disk's plastic layer correspond to the Os and 1spresent
in binary computer code. Computer files stored in this manner can be made up of
several billion etchings or more, depending on the size of the file. Because
the bumps made in the plastic are so small, optical discs can still hold large
volumes of data. In order to accommodate the large file sizes, etchings are
wound around the optical disc in a spiral shaped pattern. As we can see in the
picture below, each information spiral begins at the inner edge of the disc. By
storing information in this way, users can directly access the files they're
interested in, without having to open any others.
Reading
from an Optical Disk
While
the individual structure of an optical drive can vary, most are functionally
very similar to the disk players commonly found in laptops, such as the one
shown above. In these players, optical discs can be detachably secured to a
mount that allows the disc to rotate quickly and freely. In order to read the
disc and access the data stored there, the drive uses a laser to shine a light
on the bumps and gaps etched into its plastic layer. As the disc is rotated by
a motor, the drive's photocell is able to interpret how this laser's light gets
reflected back from the surface of the disk, and discern the difference between
bumps and gaps within the plastic layer. From here, the computer translates
this information backinto binary code so the disk's stored files can be opened
and read.
(ii)
Cache Memoryকী? Computer এর main memory-এর সাথে এর পার্থক্য কী?
Answer:
Cache
memory is an extremely fast memory type that is placed between RAM and CPUand acts
as a buffer between two. Cache memory is used to reduce the average time to
access datafrom the Main memory. The cache is a smaller and faster memory which
stores copies of thedata from frequently used main memory locations.
Comparison
between Cache Memory and Main Memory:
Main Memory |
Cache Memory |
Main memory is also known as Random Access Memory. It is a memory unit
that directly interacts with the central processing unit (CPU). |
Cache memory is used to store frequently accessed data in order to
quickly access the data whenever it is required. |
Proximity is Comparatively closer with CPU |
Proximity is Comparatively far with CPU |
Speed is Comparatively slow |
Speed is Comparatively fast |
It is a part of the hard drive (secondary storage) |
Located on the processor itself |
Less expensive |
Very expensive |
1.
(i) Propositional logic ও Predicate Logic উদাহরণবর্ণনাকরুন।
Answer:
Propositional
logic: A proposition is a collection of declarative statements that has either
atruth value "true" or a truth value "false". A
propositional consists of propositional variablesand connectives. We denote the
propositional variables by capital letters (A, B, etc). Theconnectives connect
the propositional variables. Some examples of Propositions are givenbelow:
"Man
is Mortal", it returns truth value "TRUE"
"12
+9= 3 - 2", it returns truth value "FALSE"
The
following is not a Proposition:
"A
is less than 2". It is because unless we give a specific value of A, we
cannot saywhether the statement is true or false.
Predicate
Logic: A predicate is an expression of one or more
variables defined on somespecific domain. A predicate with variables can be
made a proposition by either assigning avalue to the variable or by quantifying
the variable.
The
following are some examples of predicates
Let
E(x, y) denote "x = y"
Let
X(a, b, c) denote "a +b+c=0"
Let
M(x, y) denote "x is married to y"
ii)
Knowledge কী? Human
Knowledge কে Computer এ প্রকাশ করার একটি flow diagram দেখান
Answer:
Knowledge is a familiarity, awareness, or understanding of someone or
something,such as facts, information, descriptions, or skills, which is
acquired through experience oreducation byperceiving, discovering, or learning.
Knowledge can refer to a theoretical orpractical understanding of a subject.
2.
(i) DBMS কী? একটি Database কে normalize করার পদ্ধতি গুলো বর্ণনা করুন।
Answer:
DBMS:
A database management system (DBMS) is a software package designed to define,
manipulate, retrieve and manage data in a database. A DBMS generally
manipulates the data itself, thedata format, field names, record structure and
file structure. Some other DBMS examples include: MySQL, SQL Server.
Normalization:
Normalization is a database design technique that organizes tables in a manner
that reduces redundancy and dependency of data. Normalization divides larger
tablesinto smaller tables and links them using relationships. The purpose of
Normalization is toeliminate redundant data and ensures data is stored
logically. The database normalization process is divided into following the
normal form:
First
Normal Form (1NF) Rules:
A
relation will be 1NF if it contains an atomic value.
It
states that an attribute of a table cannot hold multiple values. It must hold
onlysingle-valued attribute.
First
normal form disallows the multi-valued attribute, composite attribute, and their
combinations.
Second
Normal Form (2NF) Rules:
In
the 2NF, relational must be in 1NF.
In
the second normal form, all non-key attributes are fully functional
dependentthe primary key
Third
Normal Form (3NF) Rules:
A
relation will be in 3NF if it is in 2NF and not contain any transitive
partialdependency.
3NF
is used to reduce the data duplication. It is also used to achieve the
dataintegrity.
If
there is no transitive dependency for non-prime attributes, then the relation
must bein third normal form.
A
relation is in third normal form if it holds atleast one of the following
conditions for everynon-trivial function dependency X →Y.
X
is a super key.
Y
is a prime attribute, i.e., each element of Y is part of some candidate key.
Boyce-Codd
Normal Form (BCNF):
It
should be in the Third Normal Form.
And,
for any dependency A →B, A should be a super key.
Fourth
normal form (4NF):
A
relation will be in 4NF if it is in Boyce Codd normal form and has no
multi-valueddependency.
For
a dependency A → B, if for a single value of A, multiple values of B exists,
thenthe relation will be a multi-valued dependency.
(ii)
Recursion কী? Recursion পদ্ধতির একটি
Simple C programming এর
Code লিখুন।
Answer:
The
process in which a function calls itself directly or indirectly is called
recursion and thecorresponding function is called as recursive function. Using
recursive algorithm, certainproblems can be solved quite easily. In the
following example, recursion is used to calculatethe factorial of a number.
#include<stdio.h>
int
fact (int n) {
f(n==0||n==1)
return
1;
else
return
n*fact (n-1);
}
int
main() {
int
n, f;
printf("Enter
number whose factorial you want to calculate: ");
scanf("%d",&n);
f
= fact (n);
printf("factorial=
%d", f);
return
0;
}
Output:
Enter
number whose factorial you want to calculate? 5
Factorial
= 120
3.
(i) Formatted Input/Output
Statement কাকে বলে? Key Board থেকে কিভাবে
input নেয়া যায়? %d এর অর্থ কী?
Answer:
Formatted console input/output functions are used to take one or more inputs
from the user at console and it also allows us to display one or multiple
values in the output to the user at the console. This function is used to read
one or multiple inputs from the user at the console.
Input
from keyboard in C:
In
C programming, scanf() is one of the commonly used function to take input from
the user. The scanf() function reads formatted input from the standard input
such as keyboards.
#include
<stdio.h>
int
main() {
int
testInteger;
printf("Enter
an integer: ");
scanf("%d",
&testInteger);
printf
("Number =%d", testInteger);
return
0;
}
Output:
Enter
an integer: 4
Number
= 4
%d
is a format specifier used to identify by printf, scanf; or other functions
that the operation will be done on a variable having the format of an integer.
For example:
printf("%d",n);
//tells to print integer n.
(ii)
if...else statement এর
format লিখ
১+৩+৫+৭…..+n
সিরিজটির যোগফল নির্ণয়ের জন্য C language এ একটি প্রোগ্রাম লিখ।
Answer:
If
else statements in C is used to control the program flow based on some
condition. The ifstatement may have an optional else block. The syntax
of the if...else statement is:
if
(test expression) {
//
statements be executed if the test expression is
true
}
else{
//
statements to be executed if thetest expression is
false
}
1+3+5+7..........+n
সিরিজটির যোগফল নির্ণয়ের জন্য
C language এ একটি প্রোগ্রাম:
#include
<stdio.h>
void
main() {
int
i, n, sum=0;
printf("Input
number of terms: ");
scanf("%d",&n);
printf("\nThe
odd numbers are:");
for
(i=1;i<=n; i++)
{
printf("%d
",2*1-1);
sum+=2*i-1;
}
printf
("\nThe Sum of odd Natural Number upto %d terms : %d \n", n, sum) ;
}
Sample
Output:
Input
number of terms: 10
The
odd numbers are: 1 3 5 7 9 11 13 15 17 19
The
Sum of odd Natural Number up to 10 terms: 100
4.
(i) Computer network কী? বিভিন্ন প্রকার Computer network সম্পর্কে আলোচনা করুন।
Answer:
A
computer network is a system in which multiple computers are connected to each
other for share information and resources.
Different
types of Computer network:
Local Area Network: A Local Area Network (LAN) is a group of computer and peripheral devices which are connected in a limited area such as school, laboratory, home, and office building. It is a widely used network for sharing resources like files, printers, games, and other application. The simplest type of LAN network is to connect computers and a printer in someone's home or office. In general, LAN can be used as one type of transmission medium.
Metropolitan Area Networks: A Metropolitan Area Network or MAN is consisting of a computer network across an entire city, college campus, or a small region. This type of network is large than a LAN, which is mostly limited to a single building or site.
Wide Area Networks: WAN (Wide Area Network) is another important computer network that is speeded across a large geographical area. WAN network system could be a connection of a LAN which connects with other LAN's using telephone lines and radio waves. It is mostly limited to an enterprise or an organization.
Personal
Area Networks: PAN is a computer network formed around
a person. It generally consists of a computer, mobile, or personal digital
assistant. PAN can be used for establishing communication among these personal
devices for connecting to a digital network and the internet.
(i) E-Commerce কী? E-Commerce-এর প্রকারভেদ উল্লেখ করুন। Search engine কী? এর কয়েকটি উদাহরণ দিন।
Answer:
E-Commerce: E-Commerce refers to any purchasing transaction that occurs online. The buying and selling of products, services, and digital products through the Internet all fall under the umbrella that is e-Commerce. These exchanges cover a vast array of business types, industry verticals, and product offerings.
Business
to Business: A website following the B2B business
model sells its products to an intermediate buyer who then sells the product to
the final customer. As an example, a wholesaler places an order from a company's
website and after receiving the consignment, sells the end product to the final
customer who comes to buy the product at one of its retail outlets. Business to
Consumer: A website following the B2C business model sells its products
directly to a customer. A customer can view the products shown on the website.
The customer can choose a product and order the same. The website will then
send a notification to the business organization via email and the organization
will dispatch the product/goods to the customer.
Consumer
to Consumer: A website following the C2C business
model helps consumers to sell their assets like residential property, cars,
motorcycles, etc., or rent a room by publishing their information on the
website. Website may or may not charge the consumer for its services. Another
consumer may opt to buy the product of the first customer by viewing the
post/advertisement on the website.
Consumer
to Business: In this model, a Consumer approaches a
website showing multiple business organizations for a particular service. The
consumer places an estimate of amount he/she wants to spend for a particular
service. For example, the comparison of interest rates of personal loan/car
loan provided by various banks via websites. A business organization that
fulfills the consumer's requirement within the specified budget Approaches the
customer and provides its services.
Business
to Government: B26 model is a variant of B2B model.
Such websites are used by governments to trade and exchange information with
various business organizations. Such websites are accredited by the government
and provide a medium to businesses to submit application forms to the
government.
Government to Business: Governments use B2G model websites to approach business organizations. Such websites support auctions, tenders, and application submission functionalities.
Search
Engine:
A
search engine is software, usually accessed on the Internet that searches
database of information according to the user's query. The engine provides a
list of results that best match what the user is trying to find. The most
popular and well-known search engine is Google. Other popular search engines
include AOL, Ask.com, Baidu, Bing, and Yahoo.
7.
(i) Logic gate কী? মৌলিক Logic gate কয়টি ও কী কী?
সত্যক সারণি সহ আলোচনা করুন।
Answer:
A logic gate is an idealized or physical electronic device implementing the
Boolean function, a logical operation performed on one or more binary inputs
that produces a single binary output.
There
are three types of basic logic gate. (i) AND (ii) OR (iii) NOT
AND
gate:
The
AND gate gives an output of 1 if both the two inputs are 1, it gives 0
otherwise. An AND gate is a digital circuit that has two or more inputs and
produces an output by performing logical AND operation to all those inputs. It
is optional to represent the Logical AND with the symbol ‘.'. The following
table shows the truth table of 2-input AND gate.
A |
B |
Y=A.B |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
1 |
Here
A, B are the inputs and Y is the output of two input AND gate. If both inputs
are '1'.The following figure shows the symbol of an AND gate, which is having
two inputs A, B andthen only the output, Y is ‘1’. For remaining combinations
of inputs, the output, Y is '0'.
The following figure shows the symbol of an AND gate, which is having two inputs A,AB and one output, Y.
OR
gate:
The
OR gate gives an output of 1 if either of the two inputs are 1, it gives O
otherwise. An OR gate is a digital circuit that has two or more inputs and
produces an output by performing logical OR operation of all those inputs. This
logical OR is represented with the symbol ‘+’.
The
following table shows the truth table of 2-input OR gate.
A |
B |
Y=A+B |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
1 |
1 |
1 |
1 |
Here
A, B are the inputs and Y is the output of two input OR gate. If both inputs
are ‘0', then only the output, Y is ‘0’. For remaining combinations of inputs,
the output, Y is 'l'.
The
following figure shows the symbol of an OR gate, which is having two inputs A,
B and one output, Y.
NOT
gate:
The
NOT gate gives an output 0 of 1 input and vice-versa. A NOT gate is a digital
circuit thathas single input and single output. The output of NOT gate is the
logical inversion of theinput. Hence, the NOT gate is also called as inverter.
The following table shows the truthtable of NOT gate.
A |
Y= |
0 |
1 |
1 |
0 |
Here
A and Y are the input and output of NOT gate respectively. If the input, A is '0’,
thenthe output, Y is ‘1”. Similarly, if the input, A is '1', then the output, Y
is '0'. The followingfigure shows the symbol of NOT gate, which is having one
input, A and one output, Y.
This
NOT gate produces an output Y, which is the complement of input, A.
(i)
R-S Flip-flop এর সত্যক সারণি ও বৈশিষ্ট্য আলোচনা করুন।
Answer:
There
are majorly 4 types of flip flops, with the most common one be most common one
being flip-flop stands for SET-RESET flip-flops. SR flip-flop operates with
only positive clock transitions or negative clock transitions. Whereas, SR
latch operates with enable signal. The circuit diagram of SR flip-flop is shown
in the following figure.
This
circuit has two inputs S & R and two outputs Q(t) & Q(t)'. The
operation of SR flip flop is similar to SR Latch. But, this flip-flop affects
the outputs only when positive transition of the clock signal is applied
instead of active enable. The following table shows the state table of SR
flip-flop.
S |
R |
Q(t+1) |
0 |
0 |
Q(t) |
0 |
1 |
0 |
1 |
0 |
1 |
1 |
1 |
|
Here,
Q(t) & Q(t+1) are present state & next state respectively. So, SR
flip-flop can be used for one of these three functions such as Hold, Reset
& Set based on the input conditions, when positive transition of clock
signal is applied. The following table shows the characteristic table of SR
flip-flop.
Present State |
Present State |
Next State |
|
S |
R |
Q(t) |
Q(t+1) |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
1 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
1 |
1 |
1 |
1 |
0 |
X |
1 |
1 |
1 |
X |
৪. (i) MVC framework কী? এর সুবিধা গুলো লিখুন।
Answer:
The Model-View-Controller (MVC) is an architectural pattern that separates an application
into three main logical components: the model, the view, and the controller.
Each of these components is built to handle specific development aspects of an
application. MVC is one of the most frequently used industry-standard web
development framework to create scalable and extensible projects.
Advantages
of MVC framework:
Development
of the application becomes faster.
Easy
for multiple developers to collaborate and work together.
Easier
to update the application.
Easier
to Debug as we have multiple levels in the application.
(ii)
Software development এর ধাপ সমূহ সংক্ষেপে বর্ণনা করুন।
Answer:
A typical Software Development Life Cycle consists of the following stages -
Stage
1: Planning and Requirement Analysis
The
requirement is the first stage in the SDLC process. It is conducted by the senior
team members with inputs from all the stakeholders and domain experts in the
industry. Planning for the quality assurance requirements and reorganization of
the risks involved is also done at this stage. This stage gives a clearer
picture of the scope of the entire project and the anticipated issues,
opportunities, and directives which triggered the project. Requirements
Gathering stage need teams to get detailed and precise requirements. This helps
companies’ to finalize the necessary timeline to finish the work of that
system.
Stage
2: Defining Requirements
Once
the requirement analysis is done the next step is to clearly define and
document the product requirements and get them approved from the customer or
the market analysts. This is done through an SRS (Software Requirement
Specification) document which consists of all the product requirements to be
designed and developed during the project life cycle.
Stage
3: Designing the Product Architecture
SRS
is the reference for product architects to come out with the best architecture
for the product to be developed. Based on the requirements specified in SRS,
usually more than one design approach for the product architecture is proposed
and documented in a DDS – Design Document Specification.
Stage
4: Building or Developing the Product
In
this stage of SDLC the actual development starts and the product is built. The
programming code is generated as per DDS during this stage. If the design is
performed in a detailed and organized manner, code generation can be
accomplished without much hassle.
Stage
5: Testing the Product
This
stage is usually a subset of all the stages as in the modern SDLC models, the testing
activities are mostly involved in all the stages of SDLC. However, this stage
refers to the testing only stage of the product where product defects are
reported, tracked, fixed and retested, until the product reaches the quality
standards defined in the SRS.
Stage
6: Deployment
Once
the software testing phase is over and no bugs or errors left in the system
then the final deployment process starts. Based on the feedback given by the
project manager, the final software is released and checked for deployment
issues if any.
Stage
7: Maintenance
Once
the system is deployed, and customers start using the developed system, following
3activities occur
Bug
fixing - bugs are reported because of some scenarios which are not tested at
all
Upgrade
- Upgrading the application to the newer versions of the Software
Enhancement
- Adding some new features into the existing software
The main focus of this SDLC phase is to ensure that needs continue to be met and that the to perform as per the specification mentioned in the first phase.