What is NAT and CGNAT Explained -

Network Address Translation (NAT) is a core networking concept that allows multiple devices in a private network to share a single public IP address. It is widely used in home networks and by Internet Service Providers (ISPs).

What is NAT?

NAT translates private IP addresses into a public IP address when traffic exits a network. This allows devices with private addresses (such as 192.168.x.x) to communicate with the internet.

Types of NAT

Static NAT: One-to-one mapping between private and public IP
Dynamic NAT: Pool of public IPs used dynamically
PAT (Port Address Translation): Multiple devices share one IP using ports

What is CGNAT?

Carrier-Grade NAT (CGNAT) is used by ISPs to allow many customers to share a limited number of public IP addresses.

In CGNAT environments, your device does not receive a public IP directly. Instead, it is placed behind multiple layers of NAT.

Why ISPs Use CGNAT

IPv4 address shortage
Cost reduction
Efficient IP allocation

Drawbacks of CGNAT

No direct port forwarding
Issues with gaming and VoIP
Difficulty hosting servers

How to Detect CGNAT

You can compare your router WAN IP with your public IP. If they are different, you are likely behind CGNAT.

Conclusion

NAT and CGNAT are essential technologies that keep the internet running despite IPv4 limitations. However, CGNAT introduces limitations that can affect advanced users.

What is NAT and CGNAT Explained