Understanding IP Addresses
An IP address (Internet Protocol address) is a unique numerical identifier assigned to every device connected to a network. Think of it as a digital mailing address that enables devices to find and communicate with each other over the internet or local networks.
IP addresses are fundamental to how the internet works. Every time you visit a website, send an email, or stream a video, IP addresses are working behind the scenes to route data between your device and servers around the world.
IPv4 vs IPv6: What's the Difference?
IPv4
- Format: 32-bit (4 bytes)
- Example: 192.168.1.1
- Total Addresses: ~4.3 billion
- Notation: Dotted decimal
- Header Size: 20-60 bytes
- Status: Widely used, address exhaustion
IPv6
- Format: 128-bit (16 bytes)
- Example: 2001:0db8::1
- Total Addresses: 340 undecillion
- Notation: Hexadecimal with colons
- Header Size: 40 bytes (fixed)
- Status: Modern standard, growing adoption
How IP Routing Works
When you send data over the internet, it doesn't travel directly to its destination. Instead, it's broken into small chunks called packets, each containing:
- Source IP address: Where the packet came from
- Destination IP address: Where the packet is going
- Payload: The actual data being transmitted
- Header information: Routing and control data
Routers examine the destination IP address and forward packets along the best path, hopping through multiple routers until reaching the final destination. This process is called packet switching.
IP Packet Structure
IP packets consist of two main parts:
IPv4 Header Fields
- • Version (4 bits) - IP version number
- • IHL (4 bits) - Header length
- • DSCP/ECN (8 bits) - Quality of service
- • Total Length (16 bits) - Packet size
- • TTL (8 bits) - Time to live (hop limit)
- • Protocol (8 bits) - Upper layer protocol (TCP, UDP, etc.)
- • Source/Destination IP (32 bits each)
IPv6 Header Fields
- • Version (4 bits) - IP version number
- • Traffic Class (8 bits) - QoS priority
- • Flow Label (20 bits) - Flow identification
- • Payload Length (16 bits) - Data size
- • Next Header (8 bits) - Protocol type
- • Hop Limit (8 bits) - Maximum hops
- • Source/Destination IP (128 bits each)
Public vs Private IP Addresses
IP addresses are divided into two categories:
Public IP Addresses
Globally unique and routable on the internet. Assigned by your ISP.
Example: 8.8.8.8 (Google DNS)
Private IP Addresses
Used within local networks, not routable on the internet.
Ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
Visualize IP Packets
Use our interactive protocol visualizer to parse and analyze real IP packets:
Frequently Asked Questions
What is an IP address?
An IP address (Internet Protocol address) is a unique numerical identifier assigned to every device connected to a network. It enables devices to locate and communicate with each other over the internet or local networks.
What is the difference between IPv4 and IPv6?
IPv4 uses 32-bit addresses providing about 4.3 billion unique addresses. IPv6 uses 128-bit addresses providing 340 undecillion addresses. IPv6 also offers improved routing, better security, and simplified header structure.
How does IP routing work?
IP routing forwards packets from source to destination across networks. Routers examine the destination IP address and use routing tables to determine the best path, hopping through multiple routers until reaching the final destination.
What are public and private IP addresses?
Public IP addresses are globally unique and routable on the internet. Private IP addresses (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) are used within local networks and not routable on the public internet.