Combined Bank
Senior Officer IT (Job ID-10225)
Post: Officer (IT) - Exam: 22.05.2026
Object-Oriented Programming (OOP) is a programming style where the code is built around objects. An object is a self-contained unit that holds both data (called attributes or properties) and the actions that can be performed on that data (called methods or functions). OOP helps organize large programs by breaking them into smaller, reusable, and manageable pieces.
Main Principles of OOP
1. Encapsulation
Encapsulation means hiding the internal details of an object and only showing the necessary parts to the outside world. It protects data from being changed directly and keeps the code safe.
Example: A bank account class hides the balance variable and only allows deposit or withdraw methods to change it.
2. Abstraction
Abstraction means showing only the essential features of an object while hiding the complex background details. It helps reduce complexity and makes the program easier to use.
Example: When you drive a car, you only use the steering and brakes. You do not need to know how the engine works inside.
3. Inheritance
Inheritance is a mechanism where a new class can take on the properties and methods of an existing class. It promotes code reuse and builds a relationship between parent and child classes.
Example: A Dog class inherits from an Animal class. Dog gets all properties like name and age, plus its own method like bark().
4. Polymorphism
Polymorphism means the same method name can behave differently in different situations. It allows one interface to be used for different data types or classes.
Example: A Shape class has a draw() method. Circle, Square, and Triangle classes override draw() to show different shapes.
Difference Between Method Overloading and Method Overriding
| Point | Method Overloading | Method Overriding |
|---|---|---|
| Definition | Using the same method name multiple times in the same class with different parameters. | Redefining a parent class method in a child class with the same name and parameters. |
| Class | Occurs within the same class. | Occurs between parent class and child class. |
| Parameters | Parameters must be different (number, type, or order). | Parameters must be exactly the same. |
| Return Type | Return type can be different. | Return type must be the same or compatible. |
| Binding | Compile-time (static) polymorphism. | Run-time (dynamic) polymorphism. |
| Example | add(int a, int b) and add(double a, double b). | Parent class show() and child class show() with same signature. |
Code Example of Method Overloading:
class Calculator {
int add(int a, int b) {
return a + b;
}
double add(double a, double b) {
return a + b;
}
}
Code Example of Method Overriding:
class Animal {
void sound() {
System.out.println(“Animal makes sound”);
}
}
class Dog extends Animal {
void sound() {
System.out.println(“Dog barks”);
}
}
Object-Oriented Programming (OOP)
Object-Oriented Programming (OOP) হলো একটি programming style যেখানে code objects-এর চারপাশে তৈরি করা হয়। Object হলো একটি self-contained unit যা data (attributes বা properties বলা হয়) এবং সেই data-এর উপর perform করা যেতে পারে এমন actions (methods বা functions বলা হয়) ধারণ করে। OOP large programs-কে ছোট, reusable এবং manageable pieces-এ ভাগ করে organize করতে সাহায্য করে।<
Main Principles of OOP
1. Encapsulation
Encapsulation মানে একটি object-এর internal details hide করা এবং outside world-এর কাছে শুধু প্রয়োজনীয় parts দেখানো। এটি data-কে সরাসরি change হওয়া থেকে রক্ষা করে এবং code safe রাখে।<
Example: একটি bank account class balance variable hide করে এবং শুধু deposit বা withdraw methods দিয়ে change করতে দেয়।
2. Abstraction
Abstraction মানে একটি object-এর শুধু essential features দেখানো এবং complex background details hide করা। এটি complexity কমায় এবং program ব্যবহার করা সহজ করে।
Example: গাড়ি চালানোর সময় শুধু steering এবং brakes ব্যবহার করেন। Engine ভেতরে কীভাবে কাজ করে তা জানার প্রয়োজন হয় না।
3. Inheritance
Inheritance হলো একটি mechanism যেখানে একটি new class existing class-এর properties এবং methods নিতে পারে। এটি code reuse promote করে এবং parent এবং child class-এর মধ্যে relationship তৈরি করে।
Example: একটি Dog class Animal class থেকে inherit করে। Dog name এবং age এর মতো সব properties পায়, সাথে নিজের bark() method ও থাকে।
4. Polymorphism
Polymorphism মানে একই method name বিভিন্ন situation-এ বিভিন্নভাবে behave করতে পারে। এটি একই interface বিভিন্ন data types বা classes-এর জন্য ব্যবহার করতে দেয়।
Example: একটি Shape class-এ draw() method আছে। Circle, Square এবং Triangle class-এরা draw() override করে বিভিন্ন shape দেখায়।
Difference Between Method Overloading and Method Overriding
| Point | Method Overloading | Method Overriding |
|---|---|---|
| Definition | একই class-এ একই method name বিভিন্ন parameters নিয়ে একাধিকবার ব্যবহার করা। | Child class-এ parent class-এর method-কে একই name এবং parameters নিয়ে redefining করা। |
| Class | একই class-এর মধ্যে occurs করে। | Parent class এবং child class-এর মধ্যে occurs করে। |
| Parameters | Parameters অবশ্যই different হতে হবে (number, type বা order)। | Parameters অবশ্যই exactly same হতে হবে। |
| Return Type | Return type different হতে পারে। | Return type same বা compatible হতে হবে। |
| Binding | Compile-time (static) polymorphism। | Run-time (dynamic) polymorphism। |
| Example | add(int a, int b) এবং add(double a, double b)। | Parent class-এর show() এবং child class-এর show() একই signature নিয়ে। |
Method Overloading-এর Code Example:
class Calculator {
int add(int a, int b) {
return a + b;
}
double add(double a, double b) {
return a + b;
}
}
Method Overriding-এর Code Example:
class Animal {
void sound() {
System.out.println(“Animal makes sound”);
}
}
class Dog extends Animal {
void sound() {
System.out.println(“Dog barks”);
}
}
The Software Development Life Cycle (SDLC) is a step-by-step process used to design, build, and deliver software. It helps teams plan, control, and manage the entire project from start to finish. Each phase has a clear goal and deliverable that moves the project forward.
1. Planning
In this phase, the project team defines the scope, goals, budget, and timeline. They analyze whether the project is possible and identify risks early. This phase sets the foundation for the whole project.
Example: A company decides to build an online shopping app. The team plans the features, cost, and deadline before starting work.
2. Requirement Analysis
The team collects and studies what the users and business need. They document all functional and non-functional requirements so developers know exactly what to build.
Example: The team asks users what they want in the shopping app, such as payment options, product search, and order tracking.
3. Design
This phase turns requirements into a blueprint. Architects create system designs, database models, and user interface layouts. It acts as a guide for the coding phase.
Example: Designers create wireframes showing how the app screens will look, and architects plan the database tables for users and products.
4. Implementation (Coding)
Developers write the actual code based on the design documents. This is the phase where the software is built. Developers follow coding standards and best practices.
Example: Developers write code in Java or Python to build the login page, product catalog, and payment gateway.
5. Testing
The testing team checks the software for bugs and errors. They run test cases to verify that the application meets requirements and works correctly. Different types of testing like unit, integration, and system testing are performed.
Example: Testers check if a user can add items to cart, make payment, and receive an order confirmation email.
6. Deployment
Once testing is complete, the software is released to the live environment for users. This may be done all at once or in stages depending on the strategy.
Example: The shopping app is launched on the Play Store and App Store for customers to download and use.
7. Maintenance
After release, the team monitors the software, fixes bugs, and adds new features. This phase continues throughout the life of the software to keep it running smoothly.
Example: The team releases updates to fix a login bug and adds a new discount coupon feature based on user feedback.
Summary Table:
| Phase | Goal | Example |
|---|---|---|
| Planning | Define scope, budget, and timeline | Plan an online shopping app project |
| Requirement Analysis | Collect and document user needs | List features like payment and search |
| Design | Create system and UI blueprint | Draw wireframes and database layout |
| Implementation | Write the actual code | Code login and product pages |
| Testing | Find and fix bugs | Test cart, payment, and email flow |
| Deployment | Release software to users | Launch app on Play Store |
| Maintenance | Fix issues and add updates | Fix login bug, add coupon feature |
Phases of the Software Development Life Cycle (SDLC)
Software Development Life Cycle (SDLC) হলো একটি step-by-step process যা software design, build এবং deliver করতে ব্যবহৃত হয়। এটি teams-কে পুরো project শুরু থেকে শেষ পর্যন্ত plan, control এবং manage করতে সাহায্য করে। প্রতিটি phase-এর একটি clear goal এবং deliverable থাকে যা project এগিয়ে নিয়ে যায়।
1. Planning
এই phase-এ project team scope, goals, budget এবং timeline define করে। তারা project feasible কিনা তা analyze করে এবং early risks identify করে। এই phase পুরো project-এর foundation তৈরি করে।
Example: একটি company online shopping app তৈরি করতে চায়। Team features, cost এবং deadline plan করে কাজ শুরুর আগেই।
2. Requirement Analysis
Team users এবং business-এর প্রয়োজনীয়তা collect এবং study করে। তারা সব functional এবং non-functional requirements document করে যাতে developers ঠিক জানতে পারে কী build করতে হবে।
Example: Team users-কে জিজ্ঞেস করে shopping app-এ কী কী চায়, যেমন payment options, product search এবং order tracking।
3. Design
এই phase-এ requirements-কে blueprint-এ রূপান্তর করা হয়। Architects system designs, database models এবং user interface layouts তৈরি করেন। এটি coding phase-এর জন্য guide হিসেবে কাজ করে।
Example: Designers wireframes তৈরি করেন যা দেখায় app screens কেমন দেখাবে, এবং architects users এবং products-এর জন্য database tables plan করেন।
4. Implementation (Coding)
Developers design documents অনুযায়ী actual code লেখেন। এই phase-এ software তৈরি হয়। Developers coding standards এবং best practices follow করেন।
Example: Developers Java বা Python ব্যবহার করে login page, product catalog এবং payment gateway-এর code লেখেন।
5. Testing
Testing team software-এর bugs এবং errors check করে। তারা test cases run করে verify করতে যে application requirements meet করে এবং সঠিকভাবে কাজ করে। Unit, integration এবং system testing এর মতো বিভিন্ন testing types perform করা হয়।
Example: Testers check করে user cart-এ item add করতে পারে কিনা, payment করতে পারে কিনা এবং order confirmation email পায় কিনা।
6. Deployment
Testing complete হলে software live environment-এ release করা হয় users-এর জন্য। Strategy অনুযায়ি একবারে বা stages-এর মাধ্যমে এটি করা যেতে পারে।
Example: Shopping app Play Store এবং App Store-এ launch করা হয় customers download এবং use করার জন্য।
7. Maintenance
Release-এর পর team software monitor করে, bugs fix করে এবং নতুন features add করে। এই phase software-এর পুরো lifetime ধরে চলে যাতে এটি smoothly run করে।
Example: Team login bug fix করার জন্য এবং user feedback অনুযায়ী নতুন discount coupon feature add করার জন্য updates release করে।<
Summary Table:
| Phase | Goal | Example |
|---|---|---|
| Planning | Scope, budget এবং timeline define করা | Online shopping app project plan করা |
| Requirement Analysis | User needs collect এবং document করা | Payment এবং search এর মতো features list করা |
| Design | System এবং UI blueprint তৈরি করা | Wireframes এবং database layout draw করা |
| Implementation | Actual code লেখা | Login এবং product pages code করা |
| Testing | Bugs খুঁজে বের করে fix করা | Cart, payment এবং email flow test করা |
| Deployment | Software users-এর কাছে release করা | Play Store-এ app launch করা |
| Maintenance | Issues fix এবং updates add করা | Login bug fix, coupon feature add করা |
The OSI (Open Systems Interconnection) Model is a reference framework that explains how data travels from one device to another over a network. It divides the entire communication process into seven layers. Each layer has its own specific job and passes data to the next layer. It helps developers and network engineers understand and troubleshoot network problems easily.
The Seven Layers of the OSI Model
1. Physical Layer
This is the lowest layer. It deals with the actual physical connection between devices. It transmits raw bits (0s and 1s) through cables, switches, and hubs.
Function: Bit transmission, voltage levels, cable types, and signal timing.
Devices: Cables, hubs, repeaters, and network interface cards (NIC).<
Example: An Ethernet cable carrying electrical signals between a computer and a router.
2. Data Link Layer
This layer handles data transfer between two directly connected devices on the same network. It makes sure data is delivered without errors.
Function: Framing, MAC addressing, error detection, and flow control.
Devices: Switches and bridges.
Example: A switch uses MAC addresses to send data to the correct computer in a local network.
3. Network Layer
This layer is responsible for moving data from one network to another. It finds the best path (routing) for the data to reach its destination.
Function: Logical addressing (IP), routing, and path selection.
Devices: Routers.
Example: A router uses IP addresses to send a packet from your home network to a website server on the internet.
4. Transport Layer
This layer ensures data is delivered completely and correctly. It breaks large data into smaller segments and reassembles them at the other end.
Function: Segmentation, error recovery, and flow control.
Protocols: TCP and UDP.
Example: TCP breaks an email into small parts, sends them, and puts them back together in the right order at the receiver.
5. Session Layer
This layer creates, manages, and ends communication sessions between two devices. It keeps the conversation active and organized.
Function: Session establishment, maintenance, and termination.
Example: When you log into a video call, the session layer sets up and keeps the call active until you hang up.
6. Presentation Layer
This layer acts like a translator. It formats, encrypts, and compresses data so the application layer can understand it.
Function: Data translation, encryption, decryption, and compression.
Example: SSL/TLS encryption on a website that keeps your password safe during login.
7. Application Layer
This is the top layer where users directly interact with the network. It provides services like email, file transfer, and web browsing.
Function: User interface and network services for applications.
Protocols: HTTP, FTP, SMTP, DNS.
Example: A web browser using HTTP to load a webpage when you type www.google.com.
Summary Table:
| Layer | Name | Main Function | Example |
|---|---|---|---|
| 7 | Application | User services like web and email | Browser loading a website |
| 6 | Presentation | Encryption and data formatting | SSL encrypting login password |
| 5 | Session | Manage connection sessions | Keeping a video call active |
| 4 | Transport | Reliable data delivery | TCP sending email in parts |
| 3 | Network | Routing and IP addressing | Router sending packet to server |
| 2 | Data Link | Error-free local delivery | Switch using MAC address |
| 1 | Physical | Raw bit transmission | Ethernet cable carrying signal |
OSI (Open Systems Interconnection) Model হলো একটি reference framework যা ব্যাখ্যা করে কীভাবে data একটি device থেকে অন্য device-এ network-এর মাধ্যমে travel করে। এটি পুরো communication process-কে seven layers-এ ভাগ করে। প্রতিটি layer-এর নিজস্ব specific job আছে এবং data পরবর্তী layer-এ pass করে। এটি developers এবং network engineers-কে network problems বুঝতে এবং troubleshoot করতে সহজ করে।
OSI Model-এর Seven Layers
1. Physical Layer
এটি সবচেয়ে নিচের layer। এটি devices-এর মধ্যে actual physical connection নিয়ে কাজ করে। এটি raw bits (0s এবং 1s) cables, switches এবং hubs-এর মাধ্যমে transmit করে।
Function: Bit transmission, voltage levels, cable types এবং signal timing।
Devices: Cables, hubs, repeaters এবং network interface cards (NIC)।
Example: একটি Ethernet cable computer এবং router-এর মধ্যে electrical signals carry করে।
2. Data Link Layer
এই layer একই network-এ সরাসরি connected দুটি device-এর মধ্যে data transfer handle করে। এটি নিশ্চিত করে যে data errors ছাড়াই deliver হয়।
Function: Framing, MAC addressing, error detection এবং flow control।
Devices: Switches এবং bridges।
Example: একটি switch MAC addresses ব্যবহার করে local network-এ সঠিক computer-এ data পাঠায়।
3. Network Layer
এই layer একটি network থেকে অন্য network-এ data move করার দায়িত্বে। এটি data-এর destination-এ পৌঁছানোর জন্য best path (routing) খুঁজে বের করে।
Function: Logical addressing (IP), routing এবং path selection।
Devices: Routers।
Example: একটি router IP addresses ব্যবহার করে home network থেকে internet-এর website server-এ packet পাঠায়।
4. Transport Layer
এই layer নিশ্চিত করে যে data সম্পূর্ণ এবং সঠিকভাবে deliver হয়। এটি বড় data-কে ছোট segments-এ ভাগ করে এবং অন্য প্রান্তে সেগুলো reassemble করে।
Function: Segmentation, error recovery এবং flow control।
Protocols: TCP এবং UDP।
Example: TCP একটি email-কে ছোট ছোট parts-এ ভাগ করে পাঠায় এবং receiver-এ সঠিক order-এ জোড়া লাগায়।
5. Session Layer
এই layer দুটি device-এর মধ্যে communication sessions তৈরি, manage এবং end করে। এটি conversation active এবং organized রাখে।
Function: Session establishment, maintenance এবং termination।
Example: একটি video call-এ log in করার সময় session layer call set up করে এবং hang up না হওয়া পর্যন্ত active রাখে।
6. Presentation Layer
এই layer অনেকটা translator-এর মতো কাজ করে। এটি data format, encrypt এবং compress করে যাতে application layer এটি বুঝতে পারে।
Function: Data translation, encryption, decryption এবং compression।
Example: একটি website-এ SSL/TLS encryption যা login-এর সময় password safe রাখে।
7. Application Layer
এটি top layer যেখানে users সরাসরি network-এর সাথে interact করে। এটি email, file transfer এবং web browsing এর মতো services provide করে।
Function: User interface এবং applications-এর জন্য network services।
Protocols: HTTP, FTP, SMTP, DNS।
Example: একটি web browser HTTP ব্যবহার করে www.google.com type করলে webpage load করে।
Summary Table:
| Layer | Name | Main Function | Example |
|---|---|---|---|
| 7 | Application | User services যেমন web এবং email | Browser website load করা |
| 6 | Presentation | Encryption এবং data formatting | SSL login password encrypt করা |
| 5 | Session | Connection sessions manage করা | Video call active রাখা |
| 4 | Transport | Reliable data delivery | TCP email parts-এ পাঠানো |
| 3 | Network | Routing এবং IP addressing | Router server-এ packet পাঠানো |
| 2 | Data Link | Error-free local delivery | Switch MAC address ব্যবহার করা |
| 1 | Physical | Raw bit transmission | Ethernet cable signal carry করা |
A Computer Network is a group of two or more computers or devices that are connected together to share resources, exchange data, and communicate with each other. The connection can be made using cables, wireless signals, or optical fibers. Networks allow users to share files, printers, internet connections, and applications easily and efficiently.Key Features:
- Resource sharing: Multiple users can share hardware and software resources.
- Communication: Devices can send messages, emails, and data to each other.
- Cost saving: Reduces the need for separate devices for each user.
- Reliability: Data can be stored in multiple locations for backup.
Different Types of Computer Networks
1. PAN (Personal Area Network)
A PAN is a very small network that connects devices around a single person. It covers a short range, usually within a few meters.
Range: Up to 10 meters.
Example: A smartphone connected to wireless earbuds via Bluetooth, or a laptop connected to a wireless mouse.
2. LAN (Local Area Network)
A LAN connects computers and devices within a limited area such as a home, school, or office building. It is privately owned and offers high-speed data transfer.
Range: Up to 1 kilometer.
Example: Computers in a university lab connected to the same printer and internet connection.
3. MAN (Metropolitan Area Network)
A MAN covers a larger area than a LAN, such as a city or a large campus. It connects multiple LANs together using high-speed connections.
Range: Up to 50 kilometers.
Example: A cable TV network that serves an entire city, or a university connecting all its branches across town.
4. WAN (Wide Area Network)
A WAN spans a very large geographical area, such as a country, continent, or even the entire world. It connects multiple LANs and MANs together.
Range: Unlimited, across countries and continents.
Example: The Internet is the largest WAN. A bank connecting all its branches across different countries.
5. WLAN (Wireless Local Area Network)
A WLAN is a type of LAN that uses wireless technology (Wi-Fi) instead of cables to connect devices within a local area.
Range: Similar to LAN, but without wires.
Example: Laptops and phones connected to Wi-Fi in a coffee shop or home.
6. SAN (Storage Area Network)
A SAN is a specialized network that provides access to consolidated block-level storage. It is mainly used in data centers and enterprises.
Example: A company storing all its data on a central server that multiple departments can access securely.
Summary Table:
| Type | Full Form | Range | Example |
|---|---|---|---|
| PAN | Personal Area Network | Up to 10 meters | Bluetooth earphones with phone |
| LAN | Local Area Network | Up to 1 km | Office computers sharing printer |
| MAN | Metropolitan Area Network | Up to 50 km | City-wide cable TV network |
| WAN | Wide Area Network | Unlimited | The Internet |
| WLAN | Wireless Local Area Network | Up to 1 km (wireless) | Home Wi-Fi network |
| SAN | Storage Area Network | Data center level | Central enterprise data storage |
Computer Network হলো দুটি বা ততোধিক computers বা devices-এর একটি group যা resources share, data exchange এবং একে অপরের সাথে communicate করার জন্য connected থাকে। Connection cables, wireless signals বা optical fibers-এর মাধ্যমে করা যেতে পারে। Networks users-কে files, printers, internet connections এবং applications সহজে এবং efficiently share করতে দেয়।
Key Features:
- Resource sharing: একাধিক users hardware এবং software resources share করতে পারেন।
- Communication: Devices একে অপরের কাছে messages, emails এবং data পাঠাতে পারে।
- Cost saving: প্রতিটি user-এর জন্য আলাদা devices কেনার প্রয়োজন কমে।
- Reliability: Backup-এর জন্য data multiple locations-এ store করা যায়।
Different Types of Computer Networks
1. PAN (Personal Area Network)
PAN হলো একটি খুব ছোট network যা একটি person-এর চারপাশের devices connect করে। এটি অল্প range cover করে, সাধারণত কয়েক মিটারের মধ্যে।
Range: 10 meters পর্যন্ত।
Example: Bluetooth-এর মাধ্যমে smartphone wireless earbuds-এর সাথে connected, বা laptop wireless mouse-এর সাথে connected।
2. LAN (Local Area Network)
LAN একটি limited area যেমন home, school বা office building-এর মধ্যে computers এবং devices connect করে। এটি privately owned এবং high-speed data transfer offer করে।
Range: 1 kilometer পর্যন্ত।
Example: একটি university lab-এর computers একই printer এবং internet connection share করে।
3. MAN (Metropolitan Area Network)
MAN একটি LAN-এর চেয়ে বড় area যেমন city বা large campus cover করে। এটি multiple LANs-কে high-speed connections-এর মাধ্যমে একসাথে connect করে।
Range: 50 kilometers পর্যন্ত।
Example: একটি city-তে cable TV network, বা university তার সব branches-কে town জুড়ে connect করে।<
4. WAN (Wide Area Network)
WAN একটি very large geographical area যেমন country, continent বা পুরো world জুড়ে বিস্তৃত থাকতে পারে। এটি multiple LANs এবং MANs-কে একসাথে connect করে।
Range: Unlimited, countries এবং continents জুড়ে।<
Example: Internet হলো সবচেয়ে বড় WAN। বিভিন্ন countries-এ branches থাকা একটি bank তাদের সব অফিস connect করে।
5. WLAN (Wireless Local Area Network)
WLAN হলো LAN-এর একটি type যা cables ছাড়াই wireless technology (Wi-Fi) ব্যবহার করে local area-তে devices connect করে।
Range: LAN-এর মতোই, কিন্তু wires ছাড়া।
Example: Coffee shop বা home-এ Wi-Fi-এর মাধ্যমে laptops এবং phones connected।<
6. SAN (Storage Area Network)
SAN হলো একটি specialized network যা consolidated block-level storage access provide করে। এটি মূলত data centers এবং enterprises-এ ব্যবহৃত হয়।
Example: একটি company তার সব data একটি central server-এ store করে যা multiple departments securely access করতে পারে।
Summary Table:
| Type | Full Form | Range | Example |
|---|---|---|---|
| PAN | Personal Area Network | 10 meters পর্যন্ত | Bluetooth earphones phone-এর সাথে |
| LAN | Local Area Network | 1 km পর্যন্ত | Office computers printer share করা |
| MAN | Metropolitan Area Network | 50 km পর্যন্ত | City-wide cable TV network |
| WAN | Wide Area Network | Unlimited | Internet |
| WLAN | Wireless Local Area Network | 1 km পর্যন্ত (wireless) | Home Wi-Fi network |
| SAN | Storage Area Network | Data center level | Central enterprise data storage |
Taking a Username and Password as input.
Checking the database.
If correct: Granting access.
If wrong: Adding 1 to a "failed attempts counter.
Access denied block the account if the counter reaches 3.
- On-demand self-service: Users can access computing resources automatically without needing human interaction with the provider.
- Broad network access: Services are available over the internet through standard devices like laptops, tablets, and phones.
- Resource pooling: The provider shares computing resources among multiple users dynamically based on demand.
- Rapid elasticity: Resources can be scaled up or down quickly as needed, often automatically.
- Measured service: Usage is monitored and billed according to actual consumption, like electricity or water.
- Data Storage and Backup: Services like Google Drive, Dropbox, and iCloud store files securely online.
- Software as a Service (SaaS): Applications like Gmail, Microsoft 365, and Zoom run directly from the cloud without local installation.
- Platform as a Service (PaaS): Developers use cloud platforms like Heroku and Google App Engine to build and deploy applications.
- Infrastructure as a Service (IaaS): Companies rent virtual servers and storage from providers like AWS and Azure instead of buying hardware.
- Big Data Analytics: Cloud tools process and analyze massive amounts of data for business insights.
- Disaster Recovery: Cloud backup ensures business continuity after hardware failure or cyberattacks.
- On-demand self-service: Users provider-এর সাথে human interaction ছাড়াই automatically computing resources access করতে পারেন।
- Broad network access: Services standard devices যেমন laptops, tablets এবং phones-এর মাধ্যমে internet-এর উপর available।
- Resource pooling: Provider multiple users-এর মধ্যে dynamically demand অনুযায়ী computing resources share করে।
- Rapid elasticity: Resources প্রয়োজন অনুযায়ী দ্রুত scale up বা scale down করা যায়, প্রায়শই automatically।
- Measured service: Usage monitor করা হয় এবং actual consumption অনুযায়ী bill করা হয়, বিদ্যুৎ বা পানির মতো।
- Data Storage and Backup: Google Drive, Dropbox এবং iCloud এর মতো services files securely online store করে।
- Software as a Service (SaaS): Gmail, Microsoft 365 এবং Zoom এর মতো applications local installation ছাড়াই cloud থেকে সরাসরি run করে।
- Platform as a Service (PaaS): Developers Heroku এবং Google App Engine এর মতো cloud platforms ব্যবহার করে applications build এবং deploy করে।
- Infrastructure as a Service (IaaS): Companies AWS এবং Azure এর মতো providers থেকে virtual servers এবং storage rent করে hardware কেনার পরিবর্তে।
- Big Data Analytics: Cloud tools massive amounts of data process এবং analyze করে business insights-এর জন্য।
- Disaster Recovery: Cloud backup hardware failure বা cyberattacks-এর পর business continuity নিশ্চিত করে।
(a) How many hits do you need en borrow to make 4 subsets?
(b) What is the new Subnet Mask in dotted-decimal format?
(c) Write down the Network Address, the First Usable IP, and the Broadcast Address for the second subnet created. Show your calculation.
(a) Number of bits to borrow
To create 4 subnets, we use the formula: 2^n = 4
So, n = 2 bits must be borrowed from the host part.
(b) New Subnet Mask
Original network: /24
Borrowed bits: 2
New prefix: /26
Subnet mask = 255.255.255.192
(c) Second Subnet Details
Block size = 256 – 192 = 64
Subnets are:
1st: 192.168.10.0 – 192.168.10.63
2nd: 192.168.10.64 – 192.168.10.127
So for the second subnet:
Network Address: 192.168.10.64
First Usable IP: 192.168.10.65
Broadcast Address: 192.168.10.127
- Protects sensitive data: Keeps personal information, financial records, and business secrets safe from thieves.
- Prevents financial loss: Stops hackers from stealing money or causing costly damage to systems.
- Maintains privacy: Ensures that private conversations, photos, and documents remain confidential.
- Ensures business continuity: Helps companies keep running even when facing cyber attacks.
- Builds trust: Customers feel safe using services that protect their information properly.
- Strong passwords and MFA: Use complex passwords and Multi-Factor Authentication to add extra layers of protection.
- Firewalls: Install firewalls to block unauthorized access to networks and systems.
- Antivirus software: Use updated antivirus programs to detect and remove malware.
- Regular updates: Keep operating systems and applications patched to fix security holes.
- Data encryption: Encrypt sensitive files so even if stolen, they cannot be read without the key.
- Regular backups: Create copies of important data to recover quickly after an attack.
- User awareness training: Teach employees and users to recognize phishing and avoid risky behavior.
- Protects sensitive data: Personal information, financial records এবং business secrets চোরদের থেকে safe রাখে।
- Prevents financial loss: Hackers money চুরি বা systems-এর costly damage করতে পারে না তা নিশ্চিত করে।
- Maintains privacy: Private conversations, photos এবং documents confidential থাকে নিশ্চিত করে।
- Ensures business continuity: Companies cyber attacks-এর সময়েও চলতে থাকতে সাহায্য করে।
- Builds trust: Customers তাদের information properly protect করা services ব্যবহারে safe feel করে।
- Strong passwords and MFA: Complex passwords এবং Multi-Factor Authentication ব্যবহার করে extra protection layer add করা।
- Firewalls: Networks এবং systems-এ unauthorized access block করতে firewalls install করা।
- Antivirus software: Updated antivirus programs ব্যবহার করে malware detect এবং remove করা।
- Regular updates: Operating systems এবং applications patch করে security holes fix রাখা।
- Data encryption: Sensitive files encrypt করা যাতে চুরি হলেও key ছাড়া read করা যায় না।
- Regular backups: Attack-এর পর দ্রুত recover করতে important data-এর copies তৈরি করা।
- User awareness training: Employees এবং users-কে phishing recognize করতে এবং risky behavior avoid করতে শেখানো।
Encryption
Encryption is the process of converting readable plain text into unreadable scrambled text called cipher text. Only authorized parties who have the correct key can convert it back into readable form. It acts like a digital lock that protects sensitive information from being read by unauthorized people.
Types of Encryption
1. Symmetric Encryption
In symmetric encryption, the same key is used to both encrypt (lock) and decrypt (unlock) the data. It is fast and efficient but requires both sender and receiver to share the secret key safely.
Example: AES (Advanced Encryption Standard) is used to protect Wi-Fi passwords and file storage.
2. Asymmetric Encryption
In asymmetric encryption, two different keys are used: a public key to encrypt the data and a private key to decrypt it. The public key can be shared openly, but the private key is kept secret by the owner. It is slower than symmetric encryption but much safer for sharing over the internet.
Example: RSA is used in SSL certificates to secure website connections and in email encryption.
Role of Encryption in Security
- Data privacy: Even if hackers steal encrypted data, they cannot read it without the key.
- Authentication: Digital signatures use encryption to prove the identity of the sender.
- Data integrity: Encryption helps detect if data was altered or tampered with during transfer.
- Legal compliance: Many laws require businesses to encrypt personal and financial data.
- Secure communication: Online banking, messaging apps, and emails use encryption to keep conversations private.
Encryption
Encryption হলো readable plain text-কে unreadable scrambled text বা cipher text-এ রূপান্তর করার process। শুধু authorized parties যাদের সঠিক key আছে তারাই এটি আবার readable form-এ ফিরিয়ে আনতে পারে। এটি একটি digital lock-এর মতো কাজ করে যা sensitive information unauthorized people-এর কাছ থেকে protect করে।
Types of Encryption
1. Symmetric Encryption
Symmetric encryption-এ lock এবং unlock করার জন্য same key ব্যবহার করা হয়। এটি fast এবং efficient কিন্তু sender এবং receiver-কে secret key safely share করতে হয়।
Example: AES (Advanced Encryption Standard) Wi-Fi passwords এবং file storage protect করতে ব্যবহৃত হয়।
2. Asymmetric Encryption
Asymmetric encryption-এ দুটি আলাদা key ব্যবহার করা হয়: public key data encrypt করার জন্য এবং private key decrypt করার জন্য। Public key openly share করা যায়, কিন্তু private key owner-এর কাছে secret থাকে। Symmetric encryption-এর তুলনায় slower কিন্তু internet-এ share করার জন্য much safer।
Example: RSA website connections secure করার জন্য SSL certificates-এ এবং email encryption-এ ব্যবহৃত হয়।<
Role of Encryption in Security
- Data privacy: Hackers encrypted data steal করলেও key ছাড়া এটি read করতে পারে না।
- Authentication: Digital signatures encryption ব্যবহার করে sender-এর identity prove করে।
- Data integrity: Transfer-এর সময় data alter বা tamper হলে encryption detect করতে সাহায্য করে।
- Legal compliance: অনেক law businesses-কে personal এবং financial data encrypt করতে বাধ্য করে।
- Secure communication: Online banking, messaging apps এবং emails private রাখতে encryption ব্যবহার করে।
1NF (First Normal Form)
1NF is the first step in normalization. A table is in 1NF when it follows these rules:
- Atomic values: Each table cell must contain only a single value, not multiple values or lists.
- Same data type: Each column should hold values of the same type.
- Unique rows: Every row must be different from others. No repeating groups are allowed.
- Unique column names: Each column must have a distinct name.
Example of 1NF:
Before (Not in 1NF):
| StudentID | Name | Subjects |
|---|---|---|
| 101 | Alice | Math, Physics |
| 102 | Bob | Chemistry |
The “Subjects” column has two values in one cell, which breaks the atomic rule.
After (In 1NF):
| StudentID | Name | Subject |
|---|---|---|
| 101 | Alice | Math |
| 101 | Alice | Physics |
| 102 | Bob | Chemistry |
Now each cell holds a single value, and the table follows 1NF rules.
2NF (Second Normal Form)
A table is in 2NF when it is already in 1NF and has no partial dependency. This means a non-key column must depend on the entire primary key, not just a part of it. 2NF is especially important when the primary key is made of two or more columns (composite key).
Must be in 1NF first.
- No partial dependency: Every non-key attribute must depend on the whole primary key.
Example of 2NF:
Before (Not in 2NF):
Primary key = (StudentID + SubjectID).
Problem: StudentName depends only on StudentID, not on the full key. This is partial dependency.
After (In 2NF):
Student Table:
| StudentID | StudentName |
|---|---|
| 101 | Alice |
Subject Table:
| SubjectID | SubjectName |
|---|---|
| S01 | Math |
| S02 | Physics |
Enrollment Table:
| StudentID | SubjectID | Marks |
|---|---|---|
| 101 | S01 | 85 |
| 101 | S02 | 90 |
Now each non-key attribute depends on the full primary key of its own table, and partial dependency is removed.
1NF (First Normal Form)
1NF হলো normalization-এর first step। একটি table 1NF-এ থাকলে নিচের rules follow করতে হবে:
- Atomic values: প্রতিটি table cell-এ শুধু একটি single value থাকতে হবে, multiple values বা lists নয়।
- Same data type: প্রতিটি column-এ same type-এর values থাকা উচিত।
- Unique rows: প্রতিটি row অন্যদের থেকে আলাদা হতে হবে। কোনো repeating groups allowed নয়।
- Unique column names: প্রতিটি column-এর আলাদা নাম থাকা উচিত।
1NF-এর Example:
Before (1NF-এ নয়):
| StudentID | Name | Subjects |
|---|---|---|
| 101 | Alice | Math, Physics |
| 102 | Bob | Chemistry |
“Subjects” column-এ একই cell-এ দুটি value আছে, যা atomic rule break করে।<
After (1NF-এ আছে):
| StudentID | Name | Subject |
|---|---|---|
| 101 | Alice | Math |
| 101 | Alice | Physics |
| 102 | Bob | Chemistry |
এখন প্রতিটি cell-এ single value আছে এবং table 1NF rules follow করে।
2NF (Second Normal Form)
একটি table 2NF-এ থাকে যখন এটি already 1NF-এ থাকে এবং কোনো partial dependency নেই। এর মানে non-key column পুরো primary key-এর উপর depend করতে হবে, শুধু key-এর একটা অংশের উপর নয়। 2NF বিশেষভাবে গুরুত্বপূর্ণ যখন primary key দুটি বা ততোধিক column নিয়ে তৈরি হয় (composite key)।<
- প্রথমে 1NF-এ থাকতে হবে।
- No partial dependency: প্রতিটি non-key attribute পুরো primary key-এর উপর depend করতে হবে।
2NF-এর Example:
Before (2NF-এ নয়):
Primary key = (StudentID + SubjectID)।<
Problem: StudentName শুধু StudentID-এর উপর depend করে, পুরো key-এর উপর নয়। এটি partial dependency।<
After (2NF-এ আছে):
Student Table:
| StudentID | StudentName |
|---|---|
| 101 | Alice |
Subject Table:
| SubjectID | SubjectName |
|---|---|
| S01 | Math |
| S02 | Physics |
Enrollment Table:
| StudentID | SubjectID | Marks |
|---|---|---|
| 101 | S01 | 85 |
| 101 | S02 | 90 |
এখন প্রতিটি non-key attribute নিজের table-এর পুরো primary key-এর উপর depend করে এবং partial dependency remove হয়ে গেছে।
Linked List
A linked list is a linear data structure where elements (nodes) are stored in separate memory locations and connected using pointers.
Each node contains two parts: data and a pointer to the next node.
Searching
Searching is the process of finding a specific element in a data structure such as an array, linked list, or database.
It helps to check whether a value exists and locate its position.
Binary Search
Binary search is an efficient searching algorithm used on a sorted array.
It works by repeatedly dividing the search interval into half.
Steps of Binary Search:
- Find the middle element of the array.
- Compare the target value with the middle element.
- If equal, search is complete.
- If the target is smaller, search in the left half.
- If the target is larger, search in the right half.
- Repeat until the element is found or the interval becomes empty.
Condition: Binary search works only on sorted data.
Time Complexity: O(log n)
Linked List
Linked list হলো একটি linear data structure যেখানে প্রতিটি element (node) আলাদা memory location-এ থাকে এবং pointer দিয়ে একে অপরের সাথে যুক্ত থাকে।
প্রতিটি node-এ দুইটি অংশ থাকে: data এবং next node-এর pointer।
Searching
Searching হলো কোনো data structure (array, linked list, database ইত্যাদি) থেকে নির্দিষ্ট element খোঁজার process।
এটি check করে value আছে কিনা এবং তার position কোথায়।
Binary Search
Binary search হলো একটি efficient searching algorithm যা sorted array-এ ব্যবহার করা হয়।
এটি বারবার data কে half করে search করে।
Binary Search এর ধাপ:
- Array-এর middle element খুঁজে বের করা।
- Target value এবং middle element compare করা।
- সমান হলে search শেষ।
- ছোট হলে left half-এ search করা।
- বড় হলে right half-এ search করা।
- এভাবে continue করা হয় যতক্ষণ না element পাওয়া যায় বা interval শেষ হয়।
শর্ত: Binary search শুধুমাত্র sorted data-তে কাজ করে।
Time Complexity: O(log n)
Cryptocurrency is a type of digital or virtual money that uses cryptography for security. It does not exist in physical form like paper notes or coins. Instead, it operates on a decentralized network of computers, meaning no single bank or government controls it. Transactions are verified and recorded on a public ledger called a blockchain. Popular examples include Bitcoin, Ethereum, and Ripple.
Key Features:
- Digital only: No physical coins or notes exist.
- Decentralized: No central authority like a bank manages it.
- Secure: Cryptography protects transactions from fraud.
- Global: Can be sent anywhere in the world quickly.
Bitcoin
Bitcoin is the first and most well-known cryptocurrency. It was created in 2009 by an unknown person or group using the name Satoshi Nakamoto. Bitcoin allows people to send and receive payments directly without needing a bank or middleman. It uses blockchain technology to record all transactions in a transparent and tamper-proof way. The total supply of Bitcoin is limited to 21 million coins, making it scarce and valuable over time.
How Bitcoin Works:
- Mining: Powerful computers solve complex math problems to verify transactions and add them to the blockchain. Miners earn new Bitcoins as a reward.
- Wallets: Users store Bitcoin in digital wallets using private keys, which act like passwords.
- Transactions: When someone sends Bitcoin, the network validates it and records it permanently on the blockchain.
Example: A person in the USA can send Bitcoin to a friend in Japan within minutes, without paying high bank fees or waiting days for processing.
Advantages of Blockchain Technology
Blockchain is the underlying technology behind Bitcoin and most cryptocurrencies. It is a chain of blocks, where each block contains a list of transactions. Once added, the data cannot be changed or deleted.
- Transparency: All transactions are visible to everyone on the network, reducing fraud and corruption.
- Immutability: Once data is recorded, it cannot be altered or deleted, making records trustworthy.
- Decentralization: No single point of control means the system is harder to hack or shut down.
- Security: Cryptography and consensus mechanisms make it extremely difficult to tamper with data.
- Faster transactions: Cross-border payments happen in minutes instead of days.
- Lower costs: Removing middlemen like banks reduces transaction fees significantly.
- Traceability: Every transaction can be traced back to its origin, useful for supply chain and auditing.
Cryptocurrency হলো একটি digital বা virtual money যা security-এর জন্য cryptography ব্যবহার করে। এটি paper notes বা coins এর মতো physical form-এ exist করে না। পরিবর্তে, এটি computers-এর একটি decentralized network-এ operate করে, যার মানে কোনো single bank বা government এটি control করে না। Transactions public ledger যাকে blockchain বলা হয় তাতে verify এবং record করা হয়। Popular examples এর মধ্যে Bitcoin, Ethereum এবং Ripple অন্তর্ভুক্ত।<
Key Features:
- Digital only: কোনো physical coins বা notes exist করে না।
- Decentralized: কোনো central authority যেমন bank এটি manage করে না।
- Secure: Cryptography transactions-কে fraud থেকে রক্ষা করে।
- Global: দ্রুতভাবে world-এর যেকোনো জায়গায় পাঠানো যায়।
Bitcoin
Bitcoin হলো first এবং সবচেয়ে well-known cryptocurrency। এটি 2009 সালে Satoshi Nakamoto নামে একজন unknown person বা group দ্বারা তৈরি করা হয়। Bitcoin people-কে bank বা middleman ছাড়াই সরাসরি payments send এবং receive করতে দেয়। এটি blockchain technology ব্যবহার করে সব transactions transparent এবং tamper-proof way-এ record করে। Bitcoin-এর total supply 21 million coins-এ limited, যা এটি scarce এবং সময়ের সাথে valuable করে তোলে।<
Bitcoin কীভাবে কাজ করে:
- Mining: Powerful computers complex math problems solve করে transactions verify করে এবং blockchain-এ add করে। Miners নতুন Bitcoins reward হিসেবে পায়।
- Wallets: Users private keys ব্যবহার করে digital wallets-এ Bitcoin store করে, যা password-এর মতো কাজ করে।
- Transactions: কেউ Bitcoin send করলে network এটি validate করে এবং blockchain-এ permanently record করে।
Example: USA-এর একজন person minutes-এর মধ্যে Japan-এর একজন friend-কে Bitcoin পাঠাতে পারে, high bank fees pay না করে বা days অপেক্ষা না করে।<
Blockchain Technology-এর Advantages
Blockchain হলো Bitcoin এবং বেশিরভাগ cryptocurrencies-এর underlying technology। এটি blocks-এর একটি chain যেখানে প্রতিটি block transactions-এর একটি list ধারণ করে। একবার add হলে data change বা delete করা যায় না।<
- Transparency: সব transactions network-এ সবার কাছে visible, যা fraud এবং corruption কমায়।
- Immutability: একবার data record হলে alter বা delete করা যায় না, records trustworthy করে তোলে।
- Decentralization: Single point of control না থাকায় system hack বা shut down করা কঠিন।
- Security: Cryptography এবং consensus mechanisms data tamper করা extremely difficult করে তোলে।
- Faster transactions: Cross-border payments days-এর পরিবর্তে minutes-এ হয়।
- Lower costs: Banks এর মতো middlemen remove করায় transaction fees significantly কমে।
- Traceability: প্রতিটি transaction এর origin trace করা যায়, supply chain এবং auditing-এর জন্য useful।
(a) Explain what ON DELETE CASCADE means in simple English.
(b) If you delete one Manager from the database, what will automatically happen to all Employees under that manager?
(c) Explain why this is very dangerous in a real banking systers. What is the best practice and how does it fix this danger?
(a) Meaning of ON DELETE CASCADE
ON DELETE CASCADE means that if a record in the parent table is deleted, all related records in the child table will also be automatically deleted.
It maintains referential integrity automatically.
(b) Effect of deleting a Manager
If a Manager is deleted from the Managers table, then all Employees linked to that Manager via Foreign Key will also be automatically deleted from the Employees table.
(c) Why it is dangerous in banking system & best practice
Danger:
In a banking system, deleting one Manager accidentally could delete all related employee records or dependent data.
This can cause massive data loss, financial inconsistency, and system failure.
Example risk:
One wrong delete operation → many employee records permanently removed.
Best Practice:
Instead of ON DELETE CASCADE, use:
- ON DELETE RESTRICT or NO ACTION
- Soft delete (use a status field like “inactive” instead of deleting data)
How it fixes the problem:
– Prevents accidental mass deletion
– Keeps historical data safe
– Allows controlled data management and auditing
Database Concept: ON DELETE CASCADE
(a) ON DELETE CASCADE এর অর্থ
ON DELETE CASCADE মানে হলো parent table-এর কোনো record delete করলে তার সাথে সম্পর্কিত child table-এর সব record স্বয়ংক্রিয়ভাবে delete হয়ে যায়।
এটি referential integrity বজায় রাখে।
(b) Manager delete করলে কী হবে
যদি Managers table থেকে কোনো Manager delete করা হয়, তাহলে Foreign Key দিয়ে যুক্ত Employees table-এর সেই Manager-এর সব employee record স্বয়ংক্রিয়ভাবে delete হয়ে যাবে।
(c) Banking system-এ কেন বিপজ্জনক & best practice
বিপদ:
Banking system-এ ভুল করে একজন Manager delete করলে তার সাথে যুক্ত সব employee data delete হয়ে যেতে পারে।
এতে massive data loss, financial inconsistency এবং system failure হতে পারে।
Example risk:
এক ভুল delete operation → অনেক employee record permanently delete।
Best Practice:
ON DELETE CASCADE এর পরিবর্তে ব্যবহার করা উচিত:
- ON DELETE RESTRICT বা NO ACTION
- Soft delete (status field যেমন “inactive” ব্যবহার করা)
কিভাবে এটি সমস্যা সমাধান করে:
– ভুল করে mass deletion আটকায়
– পুরনো data নিরাপদ রাখে
– controlled data management এবং auditing সম্ভব করে
RAID is a technology that combines multiple hard drives into a single logical storage system.
It improves performance, reliability, and fault tolerance using techniques like data striping, mirroring, and parity.
Why servers use multiple drives instead of one big drive:
- Higher reliability: If one drive fails, data can still be recovered (depending on RAID level).
- Better performance: Data is read/write in parallel across multiple drives.
- Scalability: Storage can be expanded easily by adding more drives.
- Fault tolerance: RAID protects against data loss using redundancy.
RAID 6 Storage Calculation
Given:
Number of drives = 6
Capacity of each drive = 2 TB
RAID 6 rule:
RAID 6 uses the equivalent of 2 drives for parity.
Usable drives:
6 – 2 = 4 drives
Total usable storage:
4 × 2 TB = 8 TB
RAID-এর মূল ধারণা:
RAID হলো একটি technology যা একাধিক hard drive কে একসাথে একটি logical storage system হিসেবে ব্যবহার করে।
এটি performance, reliability এবং fault tolerance বাড়ায় (data striping, mirroring, parity ব্যবহার করে)।
Servers কেন এক বড় drive না ব্যবহার করে একাধিক drive ব্যবহার করে:
- High reliability: একটি drive নষ্ট হলেও data recover করা যায় (RAID level অনুযায়ী)।
- Better performance: একসাথে multiple drive থেকে data read/write করা যায়।
- Scalability: সহজে নতুন drive যোগ করে storage বাড়ানো যায়।
- Fault tolerance: RAID data loss থেকে protection দেয়।
RAID 6 Storage Calculation
Given:
Drive সংখ্যা = 6
প্রতিটি drive = 2 TB
RAID 6 rule:
RAID 6-এ 2টি drive parity হিসেবে ব্যবহৃত হয়।
Usable drives:
6 – 2 = 4 drive
Total usable storage:
4 × 2 TB = 8 TB
A compiler is a program that translates the entire source code of a high-level language into machine code at once.
It produces an executable file after compilation.
Interpreter:
An interpreter translates and executes the source code line by line.
It does not produce a separate executable file.
Difference between Compiler and Interpreter:
- Execution: Compiler translates whole program at once; Interpreter translates line by line.
- Speed: Compiled programs run faster; Interpreted programs run slower.
- Error Handling: Compiler shows all errors after compilation; Interpreter shows errors line by line.
- Output: Compiler produces executable file; Interpreter does not produce file.
Open Source Software
Advantages:
- Free of cost
- Source code is available for modification
- High flexibility and customization
- Large community support
- Fast bug fixing and updates
Disadvantages:
- Less official technical support
- May have security risks if not maintained properly
- Not always user-friendly
- Compatibility issues with some proprietary software
Compiler:
Compiler হলো এমন একটি program যা high-level language এর পুরো source code একসাথে machine code-এ convert করে।
এটি compile করার পর executable file তৈরি করে।
Interpreter:
Interpreter হলো এমন একটি program যা source code line by line execute করে।
এটি আলাদা executable file তৈরি করে না।
Compiler এবং Interpreter এর পার্থক্য:
- Execution: Compiler পুরো program একসাথে translate করে; Interpreter line by line করে।
- Speed: Compiler দ্রুত run করে; Interpreter ধীর।
- Error Handling: Compiler সব error একসাথে দেখায়; Interpreter line by line error দেখায়।
- Output: Compiler executable file তৈরি করে; Interpreter করে না।
Open Source Software
Advantages:
- Free of cost
- Source code modify করা যায়
- Flexible এবং customizable
- Large community support
- Fast bug fix এবং update
Disadvantages:
- Official support কম থাকে
- Security risk থাকতে পারে যদি properly maintain না করা হয়
- User-friendly নাও হতে পারে
- Proprietary software এর সাথে compatibility issue হতে পারে
General Part
2. Write an Essay in English: The impact of gig economy in Bangladesh.
3. Translate Into English:
সুষ্ঠু খাবার গ্রহণ একটি উন্নত জীবন যাপন বজায় রাখার জন্য অত্যন্ত গুরুত্বপূর্ণ।কাঁচা ফলমূল ও শাক সবজি শুধু প্রয়োজনীয় পুষ্টি সরবরাহ করে না, আমাদের সামগ্রিক শক্তি বৃদ্ধি করে। পূর্ণ শস্য দীর্ঘ মেয়াদে শক্তি যোগায় এবং শারীরিক সহনশীলতা ও বিপাকীয় ব্যবস্থার উন্নতি করে। পর্যাপ্ত পানি পান সক্রিয় ও দূর রাখে। সর্বোপরি সুষম খাদ্যাভাস দীর্ঘস্থায়ী সুস্থতা নিশ্চিত করে। দীর্ঘমেয়াদের রোগ প্রতিরোধে সহায়তা করে।
4. Translate into Bangla:
Studying abroad can feel very different at first. The food tastes unusual compared to home. People speak quickly, and it is hard to follow. Customs and traditions may seem confusing. Over time, these challenges become learning experiences.
5. General Knowledge (Write only the correct answer. Do not write the whole sentence):
A. Where was the Samatatia Jampadda located?
B. How many amendments have been made to the Constitution of Bangladesh so far?
C. Which African country is currently experiencing a famine?
D. Which five countries officially joined BRICS during its historic expansion?
E. In which year did the Bangladesh cricket team win their first Test series against Pakistan?
