Dynamic DNS (DynDNS)

Does this scenario seem familiar? Yesterday you worked from home and finished your presentation, but now you’re back at work, have to give the presentation in in a few minutes, and it’s conveniently still on your PC back at home. Wouldn’t it be great to be able to access your own PC from work? It’s possible with remote desktop connection. There is, however, the risk that this might not work, and this depends on your internet provider. This is because the provider is responsible for the fact that your computer regularly receives a new IP address, and if you don’t know this address, you can’t reach your computer. This is where dynamic DNS services (DDNS) can help.

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What is DynDNS and DDNS?

'Dynamic DNS' (DynDNS) stands for Dynamic Domain Name System (also known as 'DDNS'). This helps you to forward your home network’s constantly changing IP addresses to a fixed domain name. You have to register with a DDNS service under an available name (such as example.example.com). Your computer is always available under this address, even if you don’t know its current IP address.


There are different DDNS providers that offer free domain addresses. You can find free DynDNS services from No-IP, Dynu and ChangeiP. Some routers or NAS device providers also offer their customers free DDNS.

What is the difference between DDNS and DNS?

DDNS or DynDNS can be understood as a DNS (Domain Name System) extension. The DNS is a global directory system that knows the IP address for each registered domain to allow access to websites, e-mails, or FTP. The process works like telephone directory assistance, where current contact information is kept and issued on request. The DNS 'searches' for the IP address that belongs to the hostname (if it can’t be found in the DNS cache) and is in constant exchange with the corresponding internet service provider’s DNS database. In the best case, the request is answered with the matching IP address. IP addresses can also be translated into the respective domain names in the opposite direction. However, this is more difficult, since reverse DNS is not an internet standard requirement, and the DNS is not optimized for it.

The DDNS service procedure supports the assignment of dynamic IP addresses to a particular domain. A comparison with the internet provider’s DNS databases takes place automatically. The DynDNS automatically ensures that changes to the IP address are detected and DNS entries are updated accordingly. To connect to your computer, you only need the domain address registered in the DDNS service.


Internet providers generally assign new IP addresses to internet connections every 24 hours due to address shortages, as well as for administrative and security reasons. This is to protect online data transmissions from hacker attacks.

How does the Dynamic Domain Name System (DynDNS) work?

Since the addressing is usually done with domain names and not with IP addresses, you need a dynamic DNS that updates the constantly changing IP addresses and assigns them to a fixed domain name. Whenever the IP address of the router changes, the router reports the current IP address to the DDNS service, which updates the DNS request under its own domain and answers the IP address. If you now connect to your computer, this process is as follows:

  1. The router notifies the DDNS service of the IP address assigned by the internet provider. This is then assigned in the DynDNS to the domain name you have defined. The local server can now be reached at any time with this domain.
  2. If the IP address changes after 24 hours, the DDNS service will automatically receive the new IP address. The DDNS server answers the DNS requests and updates the new IP address under the fixed domain.
  3. If you want to connect to your computer (e.g. via remote desktop connection), you have to send a DNS request to your registered domain. The DDNS server then automatically supplies the current IP address of your internet service provider stored under the name.
  4. A client-server connection is now possible with the obtained IP address.

You must first configure the settings on your router so that the router’s DynDNS function is supported. This can usually be done quite quickly.

Possible uses for DynDNS

There are many uses for DynDNS. For example, you can:

  • Access your computer on the go (e.g. via a remote desktop connection)
  • Manage multiple operating systems on one device and send your own files back and forth online
  • Make streaming media available
  • Access your own mail server or other files from your work computer

In addition, there are many other usage scenarios of remote access via DDNS that are conceivable. The Dynamic Domain Name System (DynDNS) greatly simplifies the everyday use of computers.

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