An interactive guide to understanding network fundamentals
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Welcome to TCP/IP Networking
TCP/IP (Transmission Control Protocol/Internet Protocol) is the fundamental suite of protocols that powers the internet and most modern networks. This interactive guide will help you understand the basics of how networks function.
What you'll learn:
The TCP/IP model and its layers
How IP addressing works
How data packets travel across networks
Common networking protocols and their purposes
Network Basics Visualization
Computer A
Computer B
Router
The TCP/IP Model
The TCP/IP model divides network communication into four layers, each handling specific aspects of data transmission.
Application Layer
Provides network services directly to applications
Protocols: HTTP, FTP, SMTP, DNS
Transport Layer
Handles end-to-end communication and data integrity
Protocols: TCP, UDP
Internet Layer
Handles routing of packets across networks
Protocols: IP, ICMP, ARP
Network Interface Layer
Handles physical connection and hardware addressing
Protocols: Ethernet, Wi-Fi
Data Encapsulation
As data travels down the TCP/IP stack, each layer adds its own header information - a process called encapsulation.
Application Data
IP Addressing
IP addresses uniquely identify devices on a network. IPv4 addresses consist of four octets (8-bit numbers) separated by dots.
IPv4 Address Structure
192
168
1
10
0-255
0-255
0-255
0-255
Example: 192.168.1.10
IP Address Classes
Class
First Octet Range
Example
Use
Class A
1-127
10.0.0.1
Large networks
Class B
128-191
172.16.0.1
Medium networks
Class C
192-223
192.168.1.1
Small networks
Try It: IP Address Calculator
...
Network Address:
192.168.1.0
Broadcast Address:
192.168.1.255
IP Class:
Class C
Available Hosts:
254
Packet Transmission
Data is broken into packets for transmission across networks. Each packet contains headers and payload data.
Packet Structure
Ethernet Header
MAC Addresses
IP Header
IP Addresses
TCP/UDP Header
Ports, Sequence
Data Payload
Actual Content
Network Simulation
Client
IP: 192.168.1.10
Router 1
LAN: 192.168.1.1
WAN: 10.0.0.1
Router 2
LAN: 172.16.1.1
WAN: 10.0.0.2
Server
IP: 172.16.1.10
Network Events:
Click "Start Simulation" to begin...
Common Protocols
Protocols are standardized rules that allow devices to communicate. Here are some of the most common ones:
HTTP/HTTPS
HyperText Transfer Protocol (Secure)
Used for web browsing
Port 80 (HTTP) / 443 (HTTPS)
Request-response model
DNS
Domain Name System
Resolves domain names to IP addresses
Port 53
Hierarchical distributed database
SMTP/POP3/IMAP
Email Protocols
SMTP: Sending email (Port 25)
POP3: Receiving email (Port 110)
IMAP: Advanced email management (Port 143)
FTP
File Transfer Protocol
Used for transferring files
Port 21 (control) / 20 (data)
Supports authentication
Protocol Demonstration: DNS Lookup
> DNS lookup simulation ready...
Test Your Knowledge
Let's see how much you've learned about TCP/IP networking!
1. Which layer of the TCP/IP model is responsible for routing packets?
2. Which protocol is used to resolve domain names to IP addresses?
3. What is the primary purpose of TCP?
4. Which of the following is a private IP address range?