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) HTML 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  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 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 +++…..+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 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 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

 

. (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.

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