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What Is a Dynamic DNS (DDNS)?

Each device that connects to the internet has an Internet Protocol (IP) address, and websites on web servers are no different. However, when you navigate to a website, you do not type in a series of numbers, which would be its IP address. Instead, you type in the name of the site, such as “” The mechanism that associates webpages with their IP addresses is called the Domain Name System or DNS.

However, as more and more devices connect to the internet, a system is needed to automatically assign IP addresses to domain names. In this way, IP addresses that were no longer in use could be recycled and given to new devices. A dynamic DNS (DDNS) service does this for you, mapping the name of your website to your IP address.

What Is the Difference Between DDNS and DNS?

What is a DDNS when compared to a DNS? DDNS is like an extension of DNS, and it assigns a dynamic IP address to your domain. In this DDNS meaning, the dynamic DNS service can automatically make sure that any changes to your IP address are detected and updated. There is a variety of DDNS services available, including dynamic DNS for free as well as paid options.

A DNS, on the other hand, is not able to change automatically when a new IP address is assigned to your domain. You would need a DDNS service to ensure this happens according to your needs.

What Are the Types of Dynamic DNS?

Standards-based DDNS

The standards-based DDNS is also referred to as dynamic DNS update. This involves a network protocol that also comes with a security system. Standards-based DNS services are frequently used as extensions of the Dynamic Host Configuration Protocol (DHCP) system.


There are applications that have been developed by various companies, such as Microsoft and others, that perform DDNS services. These are often used to help systems function adequately without taking up more of an administrator’s time—time that would normally be spent adjusting the configurations of dynamic updates.

DDNS for Internet Access Devices

There are programs that automatically discover and register the IP address of the client. These are executed within the client device inside a private network. The programs connect to a DDNS provider’s system using a login name that is unique to the client. This login name is then used by the DDNS provider to connect the home network’s public IP address to the hostname, or website name, that is in the DNS.

DDNS for Security Appliance Manufacturers

Manufacturers of various security devices, such as IP cameras and digital video recorders (DVRs), can make use of DDNS services to ensure the IP addresses of their devices are automatically associated with the correct domain. This is often done using an application programming interface (API) that integrates the DDNS client with the firmware of the device.

How Does Dynamic DNS Work?

With DDNS, everything hinges on the operation of a DDNS client. This client is able to monitor IP addresses for the associated device, recognizing when it changes. Every time the IP address changes, the DDNS service also updates your IP address, making sure it is still associated with the correct web domain. This applies regardless of the kind of DDNS, such as FortiGate DDNS, those associated with security devices, and DDNS for secure sockets layer virtual private network (SSL VPN).

The functioning of DDNS also holds true regardless of the environment in which it happens, such as when you are using a network address translation (NAT) router, which connects two networks, or a root server, which is a DNS name server operating in the root zone.

Why Is DDNS Useful?

Dynamic DNS is useful for people who desire to host their own site, have access to closed-circuit television (CCTV) cameras, a certain online application, game server, or VPN from their personal computer at home. Using a DDNS is cheaper because it frees you up to use a static public IP address, which saves money. Plus, thanks to DDNS, you do not have to update your records each time your IP address has to change.

Also, for administrators who would normally have to make changes manually to DNS configurations, configured hostnames, IP addresses, and other information, a DDNS saves them considerable time. All of these configurations are done for them.

Benefits of Dynamic DNS

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With DDNS, you can access a server or website with ease. Even though the IP address changes, you will not have any interruption to your workflow, viewing, or other online activity.


Instead of a network administrator investing many hours in reconfiguring and checking settings, the DDNS can do all this work for them. This frees admins up to do more mission-critical work.


DDNS saves money because you do not have to invest crucial time and human resources in reconfiguring Transmission Control Protocol/Internet Protocol (TCP/IP) settings or make adjustments to each device’s Internet Protocol version 4 (IPv4) when there is a conflict.

Security Risks Associated with Dynamic DNS

If an attacker is using command-and-control (C&C) centers to launch malware, they can use dynamic DNS to alter the IP addresses that host the C&C. In this way, the malware campaign can send malware to various locations, and because attackers keep changing their IP address, they can be more difficult to catch. 

Also, changing the IP address may allow the attack to slip past defenses that have been programmed to stop data coming from a list of banned IP addresses known to be malicious.

Configuring the Fortinet Dynamic DNS

You can configure an external device so that it can use the Fortinet DDNS service. In this way, you can make sure that outside customers and users always have the ability to link with your organization’s firewall. You can update the IP address with the FortiGuard DDNS server if you have a FortiGuard subscription. To do this:

  1. Navigate to Network >>> DNS.
  2. Turn on FortiGuard DDNS.
  3. Choose the interface that has the dynamic connection.
  4. Choose the server with which you have an account.
  5. Put in a unique location.
  6. Select "Apply."

To use the command-line interface (CLI) to set up FortiGuard as your DDNS server, you can enter the following:

config system ddns

    edit 1

        set ddns-server FortiGuardDDNS

        set ddns-domain ""

        set monitor-interface "wan1"