Have you heard of NAT type in the context of an ISP? It's actually the type of Network Address Translation configuration used by your router. And it's an interesting topic to know about. So without further ado, in this article, we'll learn about NAT Type, its usage, and other info.

NAT in ISP Overview

What is NAT type?

As aforementioned, NAT is a configuration used by your router, that determines the devices behind the router connect to the internet and their accessibility to other devices In other words, it is a technique used by ISPs to enable multiple devices to share a single public IP address. So, devices on the private network get to connect with devices on a public network without having the need to have their own unique IP address. To understand this, let's know what exactly is an IP address? An IP address is a unique numerical label assigned to each device connected to a network that uses Internet Protocol (IP) for communication. So, it's a digital address for a device basically. They are typically represented as a series of numbers separated by periods (e.g., 192.168.1.1) in the older IPv4 format or as a series of hexadecimal numbers separated by colons in the newer IPv6 format. 

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Why does ISP use NAT?

The most obvious reason for an ISP to use NAT is to share a single public IP among multiple users, since there are a limited number of public IPv4 addresses, improving efficiency and reducing costs. And here are the types of NAT:

• NAT Type 1 (Open): This type of NAT means that the device is directly connected to the internet with a public IP and no restrictions. It is rarely used by home base users and is mostly reserved for corporate users or individuals who pay for a static public IP.
• NAT Type 2 (Moderate): The NAT Type 2 makes the router sit between the user's device and the ISP's network. Some ports are open here  while others are blocked by default. This type is used by most of the ISPs in Nepal such as Worldlink, Vianet, SUbisu, Classic Tech and CGNet.
• NAT Type 3 (Strict): This one has highly restricted NAT where moist incoming connections are blocked. In Nepal, it is found among mobile internet services from telcos like Nepal Telecom and Ncell Due to its restricted nature, online gaming might get occasional lags.

How to check the NAT Type of ISP?

You can simply follow the following process in order to check the NAT Type of your ISP.

• If you are using a Windows device, open the command prompt and input this "tracert 8.8.8.8" text .
• If the first few hops show private IP addresses (e.g., 10.x.x.x, 100.x.x.x), you are behind NAT.
• Or also, you can input this command netstat -an | find "UDP"
• If you see "ESTABLISHED", NAT is Open/Moderate. If most ports are closed, it’s Strict.
• If you want to check through a smartphone or web browser, you can go to Whatismyip.com too.