TCP/IP Model (4 Layers & Comparison with OSI)

 

🔹 What is TCP/IP Model?

The TCP/IP Model is a practical networking model developed by DARPA and used in the real Internet.
It defines how data is transmitted across networks.

🏗 4 Layers of TCP/IP Model

LayerFunction
ApplicationUser services (HTTP, FTP, DNS)
TransportEnd-to-end communication (TCP/UDP)
InternetIP addressing & routing
Network AccessMAC addressing & physical transmission

🎯 Core Responsibilities

 

🔝 Application Layer
Combines OSI Application + Presentation + Session

 

🚚 Transport Layer
Uses TCP (reliable) and UDP (fast)
Uses port numbers

 

🌍 Internet Layer
Uses IP address
Handles routing across networks

 

🔗 Network Access Layer
Handles MAC addressing + physical transmission

🔄 Data Flow

Application → Transport → Internet → Network Access

📊 OSI vs TCP/IP (Important for Interviews)

OSI ModelTCP/IP Model
7 Layers4 Layers
TheoreticalPractical
Developed by ISODeveloped by DARPA
More detailedSimplified & real-world

 

🧠 OSI to TCP/IP Mapping

OSITCP/IP
ApplicationApplication
PresentationApplication
SessionApplication
TransportTransport
NetworkInternet
Data LinkNetwork Access
PhysicalNetwork Access

 

🎓 Final Interview Answer 

👉 OSI model is a 7-layer theoretical framework for understanding network communication, while TCP/IP is a 4-layer practical model used in real-world Internet communication.

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