An IP address is a unique identifier assigned to each device connected to a network. It allows devices to communicate with each other over the internet. There are two main types of IP addresses: IPv4 and IPv6.

IPv4 addresses are 32-bit numbers, typically expressed in decimal format as four octets separated by periods (e.g., 192.168.1.1). Due to the limited number of available IPv4 addresses, IPv6 was developed. IPv6 addresses are 128-bit numbers, expressed in hexadecimal format and separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).

The transition from IPv4 to IPv6 is necessary to accommodate the growing number of devices connected to the internet, as IPv6 provides a vastly larger address space.

Types of IP Addresses

IP addresses are categorized into public and private addresses, each serving distinct purposes in networking.

Public vs. Private IP Addresses

Public IP Addresses

Globally unique and assigned by Internet Service Providers (ISPs).
Used for identifying devices on the public internet.
Required for web servers, online services, and internet-facing devices.
Example: 8.8.8.8 (Google DNS Server)

Private IP Addresses

Used within local networks (LANs) and not routable over the public internet.
Assigned by routers for devices within a home or corporate network.
Allows multiple devices to share a single public IP through Network Address Translation (NAT).
Reserved Private IPv4 Address Ranges:
- 10.0.0.0 - 10.255.255.255
- 172.16.0.0 - 172.31.255.255
- 192.168.0.0 - 192.168.255.255
Example: 192.168.1.100 (common in home networks)

Network Address Translation (NAT)

NAT (Network Address Translation) is a method that allows multiple devices on a local network to share a single public IP address. It is crucial for conserving IPv4 addresses and enabling private networks to connect to the internet.

How NAT Works

A device inside a private network (e.g., 192.168.1.2) sends a request to access a website.
The router replaces the private IP with its public IP address before sending the request to the internet.
The website responds to the router's public IP.
The router translates the public IP back to the original private IP and forwards the response to the requesting device.

Types of NAT

Static NAT: Maps a single private IP to a single public IP (one-to-one mapping).
Dynamic NAT: Assigns a public IP from a pool of available addresses.
PAT (Port Address Translation) / Overloaded NAT: The most common type, where multiple private IPs share a single public IP using different port numbers.

Why is NAT Important?

IPv4 Address Conservation: Reduces the need for public IPs by allowing private networks to use a single public IP.
Security Benefits: Hides internal network structure by masking private IPs.
Connectivity for Local Networks: Enables home and business networks to connect to the internet without needing multiple public IPs.

Understanding IP addressing, public vs. private IPs, and NAT is fundamental to networking. NAT plays a critical role in enabling efficient internet communication while addressing IPv4 limitations. As IPv6 adoption increases, NAT usage may decline, but it remains a vital part of modern networking.

Networking and IP Addresses