What is NAT (Network Address Translation)? | Pros & Con

NAT is a feature that most people don’t know but always use. In ADSL modems or Router devices such as Cisco, NAT (Network Address Translation) is built by default.

What is NAT?

What is NAT?

You must have heard the IPv4 protocol. Today, the IPv4 (Version 4) protocol for Global IP addresses is almost exhausted. If NAT did not exist, only certain people or firms would access the Internet today.

Global IP addresses provided by the ISP are divided into two. These are Dynamic IP and Static IP addresses.

The dynamic IP addresses provided by the ISP work like DHCP, and when you turn your ADSL modem off and back on, the network device will receive a new IP address. Static IP addresses provide only one Global IP address for a fee.

ICANN allocates these IP addresses used on the Internet. Millions of people spend time on the Internet every day. Do you think that IPv4 IP addresses will suffice when the number of people increases? Of course not!

NAT service has been developed to use IPv4 addresses more efficiently. A person or organization with a single Global IP address can use the NAT protocol to distribute all clients on the local network to the Internet with a single Global IP address.

What Does NAT Do?

Basically, the NAT protocol is typically configured to connect two networks. However, this protocol is used to hide internal network IP addresses. In short, it converts private IP addresses on the network into a single Global IP address and passes packets to the destination network, ensuring internal network security.

There are Private IP addresses reserved for the local area network. You can configure these IP addresses for all clients on the internal network. Depending on the structure of your network, you can also create a CIDR configuration.

Reserve IP addresses are as follows; - (65,536 IP Address) - (1,048,576 IP Address) - (16,777,216 IP Address)

When using these private IP addresses on the local network, for example, a computer with an IP address of is subjected to NAT to access the Internet.

As an example of everyday life, the ADSL modem you use at home has a Network Address Dialer feature. To check the NAT feature on your ADSL modem, first, enter the management IP address of your device in a web browser and press Enter. Once you have access to the management panel of your device, you can review the operation of this protocol in the WAN section.

Active NAT Service on ADSL Modem;

ADSL Services

NAT Advantages

The advantages of the network address converter protocol are:

  • Its main advantage is that it prevents the depletion of IPv4 addresses.
  • It provides an additional layer of security by hiding the source and destination IP addresses.
  • Offers more flexibility when connecting to the Internet.
  • If you change the service provider, it allows you to use your own private IPv4 addressing system and prevent internal address changes.

NAT Disadvantages

  • Because it keeps incoming and outgoing IPv4 addresses in its memory, it puts a load on your device’s RAM and Processor.
  • It may cause a delay in IPv4 communication.
  • It also causes a loss of traceability of IP addresses between the target and the source device.
  • Some technologies and network applications may not work as expected on a NAT-configured network.

What are NAT Types?

This protocol is divided into 3 for use. These;

Basic NAT

Basic NAT performs address translation using only one public IP address and does not use port mapping.

Dynamic NAT

Dynamic NAT, unlike Basic NAT, is the collection of IP addresses purchased by the ISP in a single pool on the network device. As a result, when a client on the network tries to access the Internet, the free public IP address will be used in the pool.

Port Address Translation (PAT)

PAT is used to connect all computers on the LAN internally with a single public IP address. PAT uses a value between 1024 and 65535 for the local port number.

PAT System

In a PAT, the router checks the address table when a computer on the LAN wants to connect to the HTTP server. If it cannot find a record of the IP address, the computer writes the IP address + port number to the table. The router then converts this computer to a Public IP address and sends the packet.

Destination: The router receives the sent IP packet and sends the packet to the destination computer on the internal network. However, the destination router cannot identify the local network address from the incoming IP packet.

How Does NAT Protocol Work? ⇒ Video

To better understand what NAT is, you can watch the video tutorial configured in Packet Tracer and also subscribe to our YouTube channel to support us.


In this article, we discussed the NAT protocol in networking, which helps prevent IP Version 4 addresses from being exhausted, and briefly discussed how it works. Finally, we explained the types and what they do. Thanks for following us!

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