A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules. Its primary function is to establish a barrier between a trusted internal network and untrusted external networks, such as the internet, to prevent unauthorized access, cyber attacks, and threats.

Packet Filtering is a firewall technique used to control network access by monitoring outgoing and incoming packets and either allowing or blocking them based on source and destination IP addresses, protocols, or port numbers. Packet filters inspect each packet in isolation without context, making real-time decisions to permit or deny traffic.

Uses:

• Firewall:
  • Protects networks from unauthorized access and cyber threats.
  • Enforces security policies and controls traffic flow.
• Packet Filtering:
  • Enhances security by blocking potentially harmful packets.
  • Controls access to specific network resources based on predefined rules.

Together, firewalls and packet filtering are essential for maintaining network security and integrity.

Network Devices:

1. Bridge:

   • Connects two or more network segments, enabling communication between them.
   • Operates at the Data Link Layer (Layer 2) of the OSI model.
   • Filters traffic based on MAC addresses, reducing collisions and improving network performance.

2. Repeater:

   • Amplifies or regenerates signals to extend the transmission distance.
   • Operates at the Physical Layer (Layer 1) of the OSI model.
   • Essential for maintaining signal strength over long distances or through multiple devices.

3. Switch:

   • Connects multiple devices within a LAN, facilitating communication between them.
   • Operates at the Data Link Layer (Layer 2).
   • Uses MAC addresses to forward data to the correct destination, improving efficiency and reducing traffic.

4. Router:

   • Connects different networks, directing data packets between them.
   • Operates at the Network Layer (Layer 3) of the OSI model.
   • Uses IP addresses to determine the best path for data transmission, enabling inter-network communication and internet connectivity.

These devices play crucial roles in managing network traffic, ensuring efficient, reliable, and secure data transmission across various network types.

Here is a simple C program to determine whether a given number is even or odd:

#include <stdio.h>

int main() {
    int number;

    // Prompt user for input
    printf("Enter an integer: ");
    scanf("%d", &number);

    // Check if the number is even or odd
    if (number % 2 == 0) {
        printf("%d is even.\n", number);
    } else {
        printf("%d is odd.\n", number);
    }

    return 0;
}

Explanation:

1. Include Standard Library: #include <stdio.h> is used to include the standard input-output library.
2. Declare Variable: An integer variable number is declared to store the user input.
3. Prompt and Read Input: The program prompts the user to enter an integer and reads it using scanf.
4. Check Even or Odd: The if statement checks if the number is even (number % 2 == 0). If true, it prints that the number is even. Otherwise, it prints that the number is odd.
5. Return Statement: The program ends with return 0;, indicating successful execution.

This concise program efficiently determines the parity of a given integer.

Software is a collection of programs, procedures, and data that instruct a computer on how to perform specific tasks. It is categorized into system software, which manages hardware and basic system operations, and application software, which provides tools for user tasks like word processing and web browsing.

Operating System (OS) Job:

The operating system is critical system software that manages computer hardware, software resources, and provides services for application software. Its main functions include:

1. Resource Management: Allocates and manages CPU time, memory space, and storage for applications.
2. File System Management: Organizes and controls data storage, enabling file creation, deletion, and access.
3. Process Management: Handles process scheduling, execution, and termination, ensuring efficient task execution.
4. Device Management: Manages input/output devices, ensuring communication between hardware and software.
5. User Interface: Provides a user interface (GUI or CLI) for user interaction with the computer system.

The OS ensures smooth and efficient operation of the computer system, enabling users and applications to perform tasks effectively.

A computer system is an integrated setup of hardware and software components designed to execute computational tasks. It includes input devices (like keyboards and mice), output devices (such as monitors and printers), storage devices (hard drives and SSDs), and crucially, the central processing unit (CPU). Software components include operating systems and applications that manage hardware resources and provide user functionality.

The CPU, often referred to as the brain of the computer, is the primary component responsible for interpreting and executing most of the commands from the computer's hardware and software. It consists of the following parts:

1. Control Unit (CU): This component directs the operation of the processor. It tells the computer's memory, arithmetic/logic unit (ALU), and input and output devices how to respond to a program's instructions.

2. Arithmetic Logic Unit (ALU): The ALU performs all arithmetic and logical operations, such as addition, subtraction, and comparison.

3. Registers: These are small, high-speed storage locations within the CPU that temporarily hold data and instructions.

4. Cache: This is a smaller, faster memory located within the CPU that stores copies of frequently accessed data from main memory (RAM), enhancing processing speed.

The CPU operates through a cycle known as the fetch-decode-execute cycle. During this cycle, the CPU fetches an instruction from memory, decodes it to determine what action is required, and then executes it. This process allows the CPU to perform complex tasks by breaking them down into simple operations.

Overall, the CPU's efficiency and speed are critical to the overall performance of the computer system, making it a pivotal component in modern computing.