Lexicon — a personal knowledge base
Clear, searchable explanations on computing, networking, programming, and security — ask a question and it lands here as a topic you can browse anytime.
23 notes across 6 categories.
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OSI Model
The complete OSI reference — every layer, its protocols, devices, headers, addressing, security, and how it maps to TCP/IP. One page, everything.
TCP vs UDP
The two transport protocols compared in full — how each works, when to use which, headers, reliability, security, and where QUIC/HTTP-3 fits.
TCP/IP Model
The 4-layer model the internet actually runs on — each layer, its protocols, how it maps to OSI, encapsulation, a real web request, and why it beat OSI.
Layer 2 & Layer 3 Networking
Layer 2 & Layer 3 Networking — Complete Notes Written for Nokia Software/QA Co-op Prep | Kalyan Gopalam | Northeastern University M.S. Cybersecurity --- Tabl…
Programming
Start Here — How to Solve a Problem
Stuck and can't solve even one problem? This is the gentle, from-zero guide to how problem solving actually works — solve by hand first, then code. A ~22 minute read.
From if/else to DSA — The Whole Path
The complete beginner journey, explained gently and in full — decisions, loops, functions, recursion, every data structure, and the core algorithms. Read it over several sittings.
Problem Solving
How to actually solve programming problems — the process, every pattern and when to use it, complexity, data structures, worked examples, and how to get good.
DSA Practice — Learn by Solving
A hands-on path through DSA: learn a pattern, solve real LeetCode problems with built-in Hint 1 / Hint 2 / Approach drop-downs, then the next pattern. A ~40 minute read + a lot of practice.
C Programming
The full C lab notebook in one place — every classic program (Part A, B and C) with code, how it works, and sample output, plus a quick reference for I/O and operators.
Python
Python from scratch — every fundamental explained clearly, building up to solving real problems, with links to the Problem Solving patterns and complexity.
Bug Bounty
Only Bug Bounty Checklist You'll Ever Need!!!
Global Manual Bug Bounty Checklist Purpose: A target-agnostic, manual-first checklist for authorized web, API, SaaS, identity, business-logic, integration, a…
Only Bug Bounty Checklist You'll Ever Need!!! V2
Global Manual Bug Bounty Checklist Purpose: A target-agnostic, manual-first checklist for authorized web, API, SaaS, identity, business-logic, integration, a…
My Notes
Python Conditional Statements - The Complete Breakdown
Python Conditional Statements — The Complete Breakdown So what even is a conditional? Your code runs top to bottom, line by line. Every line executes. That's…
Python Data Types - The Complete Breakdown
Python Data Types — The Complete Breakdown So what even is a data type? When you store something in a variable, Python doesn't just save the value — it also …
Python Dictionaries - The Complete Breakdown
Python Dictionaries — The Complete Breakdown So what even is a dictionary? A list stores things in order and you access them by position — skills[0] , skills…
Python Exception Handling - The Complete Breakdown
Python Exception Handling — The Complete Breakdown So what even is an exception? Your code is running fine. Then something goes wrong — a user types text whe…
Python Functions - The Complete Breakdown
Python Functions — The Complete Breakdown So what even is a function? You've been writing code that runs top to bottom, once, in one shot. That works for sma…
Python Lists vs Arrays — The Real Story
Python Lists vs Arrays — The Real Story Wait, does Python even have arrays? Kind of. Sort of. Not really — but also yes. Here's the thing nobody tells you up…
Python Loops - The Complete Breakdown
Python Loops — The Complete Breakdown So what even is a loop? Imagine you have a list of 1000 usernames and you want to print every single one. You could wri…
Python OOP - The Complete Breakdown
Python OOP — The Complete Breakdown So what even is OOP? You've been writing procedural code — functions, variables, loops, all running top to bottom. That w…
The f Thing in Python - f-strings
The f Thing in Python — f-strings So what even is it? Okay so imagine you're writing a text message to a friend and you want to include their name and age in…