Comprehensive Guide to Blockchain Systems, CAP Theorem, and Cryptography
1. Centralized, Decentralized, and Distributed Systems
1. Centralized System
A centralized system is a system where a single central authority or server controls the entire system. All operations and data are managed by this central authority.
Example: Traditional banking system.
Client
v
+--------------+
| Central |
| Server |
+--------------+
/ | \
v v v
Client Client Client
Features:
- Single authority controls the system.
- Data is
Systems Programming: Memory, I/O, and Concurrency
Virtual Memory and Memory Management
Virtual Memory (VM): The virtual address space is divided into fixed-size pages (standard 4KB); physical memory serves as a cache for these pages. A page table (which is per process) maps virtual pages to physical pages or marks them as invalid/unmapped.
Address Translation and Page Faults
Address Translation: The Virtual Address (VA) is composed of [VPN | VPO]. The Memory Management Unit (MMU) looks up the Virtual Page Number (VPN) in the page table to get a Page
Read MoreCore C Language Fundamentals and Practical Programs
C Program to Find the Largest of Three Numbers
#include <stdio.h>
int main() {
int a, b, c;
printf("Enter three numbers: ");
scanf("%d %d %d", &a, &b, &c);
if (a >= b && a >= c) {
printf("%d is the largest.\n", a);
} else if (b >= a && b >= c) {
printf("%d is the largest.\n", b);
} else {
printf("%d is the largest.\n", c);
}
return 0;
}C Program to Check Positive, Negative, or Zero
#include <stdio.Read More
Computer Networking and Architecture Fundamentals
Data Transmission and Networking
What is a packet?
A packet is a small unit of data sent across a network. Large files are divided into packets so they can be transmitted more efficiently.
What is a header?
A header is part of a packet. It contains the destination address and sequencing information so the packet reaches the correct device.
What is a payload?
A payload is the part of a packet that contains the actual data being sent.
What is a trailer?
A trailer is the last part of a packet. It contains
Read MoreDigital Forensics: Image, Network, and Cloud Analysis
Digital Image Forensics
Raw Image File: An unprocessed image format from high-end cameras. It is proprietary and preserves the most complete sensor data. Demosaicing is the process of converting raw sensor data into a standard, viewable image format.
Metadata and File Structure:
- EXIF Data: Stores metadata like camera make, model, and serial number.
- File Header: The beginning portion of a file containing hexadecimal values (e.g., JPEG is FFD8).
- Bitmap Files: Store graphic information as a grid of individual
Database Transactions, ACID Properties, and Deadlocks
Transaction and ACID Properties (8 Marks)
A transaction is a sequence of database operations that performs a single logical unit of work. A transaction may consist of one or more SQL statements such as INSERT, UPDATE, DELETE, and SELECT.
A transaction must be completed entirely; otherwise, all changes made by it are cancelled.
Example: Bank Fund Transfer
- Debit ₹1000 from Account A.
- Credit ₹1000 to Account B.
Both operations together form a transaction. If one operation fails, the entire transaction
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