Essential Linux Commands: System Administration and Operations
Expand Support of Mandates
man command displays a manual on the mandate, its mode of use, and its variants.
System On and Off
shutdown -h 5: Shut down the system in 5 minutes without restarting.shutdown -h now: Shut down the system immediately without rebooting.halt: Shut down the system (same as previous commands).shutdown -r 5: Shut down the system in 5 minutes and restart.shutdown -r now: Shut down the system immediately and restart.reboot: Reboot the system.startx: Start the graphical environment.
Networking Fundamentals: Protocols, Cables, and Communication
Common LAN Protocol Families
SNA, NetWare, AppleTalk, NetBEUI, and TCP/IP.
Network Architecture Definition
A layered body of network protocols enabling communication between nodes.
The OSI Model
A reference model for layered architecture in computer networks and distributed systems, proposed by ISO’s Open Systems Interconnection standard. It’s a reference, not a network architecture.
LLC Sublayer Role
Ensures error-free communication of frames built from network layer information.
Ohm’s Law and Signal Attenuation
All
Read MoreCryptography Essentials: Keys, Hashes, and Authentication
X.509 Certificate Format
An X.509 certificate is a digital certificate used to establish the identity of an entity, such as a person or a website, and ensure secure communication.
Key Components
- Version: Specifies the X.509 version (usually v3).
- Serial Number: A unique identifier for the certificate issued by the Certificate Authority (CA).
- Signature Algorithm: The algorithm used by the CA to sign the certificate (e.g., RSA or ECDSA).
- Issuer: The CA that issued the certificate (e.g., “CN=Example CA”).
Network Fundamentals Exam (Version 4.0)
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Read MoreSorting, Heaps, and Graph Algorithms
Merge sort:
#include <stdio.H>
#include <stdlib.H>
#include <string.H>
#define MAX 10000
Int noofcomparision = 0;
Void merge(int arr[], int l, int mid, int h) {
Int n1 = mid + 1 – l;
Int n2 = h – mid;
Int a[n1], b[n2];
For (int i = 0; i < n1; i++) {
A[i] = arr[i + l];
}
For (int i = 0; i < n2; i++) {
B[i] = arr[i + mid + 1];
}
Int i = 0, j = 0, k = l;
While (i < n1 && j < n2) {
Noofcomparision++;
if (a[i] <= b[j]) {
arr[k] = a[i];
Read More
Understanding Computer Fundamentals: Data, Devices, and Memory
Why People Prefer Computers
Computers work faster than humans, find information quickly, store data efficiently, and operate tirelessly.
Data Types
Numeric: Integer and real.
Text: String.
Graphics: Pictures.
Date
Sound
Input Devices
Concept Keyboards
A flat board with programmable keys, used in primary education.
Light Pen
A pen-shaped wand with light sensors to select objects on screen.
Touch Screen
A flat screen that detects touch using infrared lasers, commonly found in restaurants.