CyberSeekh

Networking Series

Lesson 2: Internet Hawa Mein Nahi Hai

The Hidden World of Submarine Cables & Data Centers.

Undersea Internet Cables Map

Part 1: The Biggest Myth - Cloud & Satellites

Jab hum "Internet" shabd sunte hain, to dimaag mein kya aata hai? Wi-Fi waves? Satellites? Ya phir "The Cloud"?

Humein lagta hai ki jab hum Instagram par photo upload karte hain, to wo hawa mein udkar America jaati hai. Ye bilkul galat hai.

Asliyat ye hai ki **Internet zameen aur samundar ke neeche hai**. Aapka data 99% time patli fiber-optic cables ke through travel karta hai, jo insaan ke baal (hair) jitni patli hoti hain.

Reality Check: Satellites (jaise Starlink) duniya ka sirf <1% internet traffic handle karte hain. Baaki 99% traffic **Submarine Cables** (Samundar ke neeche bichhi taaron) se chalta hai.

Part 2: Internet Ki Haddi (The Backbone)

Internet ko chalane ke liye poori duniya mein cables ka jaal bichha hua hai. Is system ko samajhne ke liye humein ISPs (Internet Service Providers) ko 3 levels mein samajhna hoga.

ISP Tier Structure Diagram

Tier 1, 2, and 3 ISP Structure

Tier 1 ISP (The Owners)

Ye wo companies hain jinhone samundar ke neeche cables bichhayi hain. Ye internet ke "Maalik" hain.
Ex: Tata Communications, AT&T, Verizon.
Ye kisi ko paise nahi dete, ye apna data free mein exchange karte hain.

Tier 2 ISP (Middlemen)

Ye Tier 1 se connection khareedte hain aur Tier 3 ko bechte hain.
Ex: Airtel, Jio (National Level par).
Ye country ke andar cables bichhate hain.

Tier 3 ISP (Local)

Ye aapke ghar tak internet pahunchate hain.
Ex: Tikona, Hathway, Local Cable Wala.
Hum inhein paise dete hain, ye Tier 2 ko dete hain, wo Tier 1 ko dete hain.

Data Travel: India se USA tak ka safar

Maan lo aap Mumbai mein baithe hain aur Facebook (USA) kholte hain. Data kaise travel karega?

  • Step 1: Aapka Mobile → WiFi Router.
  • Step 2: Router → Aapke Ghar ke bahar wala khamba (Tier 3 ISP).
  • Step 3: Tier 3 ISP → Tier 2 ISP (Jio/Airtel) ke Fiber Network tak.
  • Step 4: Tier 2 ISP → Mumbai ke Landing Station tak (Jahan samundar ki cable zameen se milti hai).
  • Step 5: Mumbai → Submarine Cable → Red Sea → Egypt → Europe → Atlantic Ocean → USA (Tier 1 ISP).
  • Step 6: USA Landing Station → Facebook Data Center.
Time Taken: Ye poora safar (aana aur jaana) light ki speed se hota hai. Isme mushkil se 200-300 milliseconds lagte hain.

Part 3: Data Packets - Digital Lifafay (Envelopes)

Agar aap ek 1GB ki movie bhejte hain, to wo ek baar mein nahi jaati. Internet us movie ko lakhon chhote tukdon mein tod deta hai. In tukdon ko Packets kehte hain.

Data Packet Structure

A Data Packet: Header + Payload

# Packet Structure (Ek Digital Lifafa)
-----------------------------
HEADER:
Source IP: 192.168.1.5 (Aap)
Dest IP: 157.240.16.35 (Facebook)
Sequence No: 1 of 1000
PAYLOAD:
(Movie ka chhota sa tukda)
-----------------------------

Har packet alag raste se ja sakta hai. Ho sakta hai Packet 1 Europe hokar jaye aur Packet 2 Japan hokar. Destination par pahunch kar ye wapas jud jate hain.


💻 Tech Corner: Internet Ka Rasta Dekhein

Aap khud dekh sakte hain ki aapka data kin routers aur cities se hokar guzar raha hai. Iske liye hum Traceroute command use karte hain.

Traceroute Command Output
# Windows CMD me type karein:
tracert google.com

# Linux/Mac Terminal me type karein:
traceroute google.com

# Output Example:
1 192.168.1.1 (Aapka Router)
2 10.20.30.1 (Aapka Local ISP)
3 125.16.x.x (Mumbai Gateway)
4 72.14.x.x (International Cable - Exit India)
...
12 142.250.x.x (Google Server USA)

Har line ek "Hop" (Stop) hai. Agar beech mein "Request Timed Out" aaye, to iska matlab wahan firewall laga hai jo aapko detect hone se rok raha hai.


Part 4: Security Relation (Khatra Kahan Hai?)

Ab jab aapko infrastructure samajh aa gaya, to aap attacks bhi samajh payenge.

Man in the Middle Attack

Man-in-the-Middle (MitM)

Kyunki data kayi routers se hokar guzarta hai, agar hacker kisi ek router (e.g., Free WiFi Cafe) par baitha ho, to wo aapke Packets padh sakta hai.
Solution: HTTPS/VPN (Encryption).

DDoS Attack

Agar hum server par itne Packets bhej dein ki cable jam ho jaye, to website band ho jayegi. Ye digital traffic jam hai.


📝 Final Assessment

Q1: Internet ka backbone (Backbone) kise kaha jata hai?

  • A) Satellites
  • B) Submarine Cables (Correct)
  • C) Cloud Servers

Q2: Tier 1 ISP kaun hote hain?

  • A) Local cable wale
  • B) Jo cables ke maalik hote hain (Global) (Correct)
  • C) Google aur Facebook

Q3: Data ko chhote tukdon mein todne ko kya kehte hain?

  • A) Hashing
  • B) Packets (Correct)
  • C) Zip File

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