Network Address Translation

In networking, NAT stands for Network Address Translation. It’s a method used by routers to translate private (local) IP addresses into a public IP address (and vice versa) when data is going to or coming from the internet.

Why NAT is used:

• IP address conservation: IPv4 addresses are limited. NAT allows multiple devices in a local network (like your home Wi-Fi) to share a single public IP address.

• Security: It hides internal IP addresses from the outside world.

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Types of NAT:

1. Static NAT:

   One private IP is mapped to one public IP.

   🔄 Always same mapping.

2. Dynamic NAT:

   A private IP is mapped to any available public IP from a pool.

   🔁 Not fixed.

3. PAT (Port Address Translation) – also called NAT Overload:

   Many private IPs share one public IP, distinguished using port numbers.

   🌐 This is the most common form, used in home routers.

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Example:

• Your phone has a private IP: 192.168.1.10

• Your router has a public IP: 123.45.67.89

When your phone accesses a website:

• NAT converts 192.168.1.10 ➜ 123.45.67.89:port

• The website responds to 123.45.67.89:port

• NAT converts it back to 192.168.1.10

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Let me know if you want a diagram or real-world analogy!