What is DDNS / DynDNS and what is it used for?

DDNS stands for a dynamic domain name system and is often referred to as dynamic DNS as well. In the simplest terms, it is the DDNS service that allows a user to access his computer over the internet, from anywhere across the globe. The service maps the domain names from the internet to the IP addresses.

For those of you who are wondering, what is an IP address? It is an internet protocol address that gives an identity to a networked device. It is the number by which a piece of hardware that is networked can be easily identified. Since it gives an identity to a device, it is also used in the process of communication between two devices that are connected to a network that is based on IP address, just like the internet.

Coming back to what is DDNS, it allows anyone who is hosting a web server to advertise a public name to the ones who are using it. Something very similar is done by the internet’s Domain Name System or DNS. But what sets DDNS apart is the fact that it is specifically designed in such a way to work with the Dynamic IP addresses as well. Dynamic IP addresses are the ones that are constantly changing. On the other hand, DNS works only with the static IP address or the IP address that does not change at all. It is for this reason that DDNS works well with the home networks since they receive dynamic IP addresses from their internet providers.

DDNS working simplified for you!

If you are still wondering how a DDNS service works, try and relate it to the way your phone works…Yes! You got me right, your phone works the same way the DDNS service does. There are so many phone numbers on our contact list that there is no chance we can remember them all. But our phone figures out an easy way for us. The software on the phone helps us to assign a name to every phone number. So every time we have to dial a number, we dial the individual’s name and the number assigned to the name gets dialed automatically.

Now add a twist to the situation and imagine that the number that you just saved is dynamic and keeps changing every day or maybe several times a day. This one is not going to be easy, but this is precisely the problem that is resolved by DDNS service or dynamic domain name system, but not for the cell phone but the computer with an IP address.

In the real terms, to use DDNS, the user needs to sign up with DDNS provider and then install their software on the host computer, which is the one that is used as the server (web server, file server, etc.) The installed software keeps track of all the changes that are made in a dynamic IP address. Every time the IP address changes, the installed software will contact the DDNS service which in turn will update the user’s account with a new IP address.

This makes it clear that the DDNS software can detect any change in the IP address. The visitors will be directed to the host server by the DDNS name, every time, irrespective of the times the IP address changes.

The DDNS service is required only for the networks that have a dynamic IP address and not for the ones with static IP addresses. In the case of a static IP address, the domain name needs to be mapped with the IP address just once since it remains static and the static IP addresses do not change again and again like the dynamic ones.

When should you use a DDNS service?

You should opt for a DDNS service in the following cases:

  • If you host your website from home

  • If you want to access your files from any part of the world

  • If you want to access your computer when you are away

  • If you wish to manage your home network when you are away from home.


Jonathan has a masters degree in Computer Engineering, loves programming and creating web services that help people perform various tedious tasks.

In his free time, he writes informative articles about networking and routers for RouterReset.com

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