A dynamic DNS host is a service that provides you with a static hostname (like "user.dyndns.org" or "user.no-ip.org").
Its main advantage is that you then can connect to the DNS hostname instead of your IP; this makes sense especially since IPs are usually dynamic and change on every reconnection.
This is very useful if you run server software on your computer, like a web- or FTP-server.
Once registered at a dynamic DNS host service, you can either configure your router to automatically update the DNS host with your current IP - or run a client application on your computer that watches for IP changes and tells the DNS service to update the hostname.
Still not sure how this works and what it can be used for? No problem, here some examples:
Example 1: Dynamic DNS on a home computer
You probably have a dynamic IP assigned by your internet provider, which means that it changes on each reconnection. Many ISPs even have a 24h auto-disconnect, so that your IP changes at least every 24 hours. But even if you have a static IP - once you connect to the VPN, your machine is using a different IP, the VPN IP.
So in any situation where you need to access your home computer, you will have the problem that you don't know your computers current IP unless you manually check it at IP-verifying websites like http://geoip.hidemyass.com
That's where dynamic DNS comes in - you can either configure your router to refresh the dynamic DNS hostname regularly with your current IP (if supported by your router), or you simply run a dynamic DNS client application on your computer which does the same job.
Now once you need to access your computer externally, e.g. to stream media to your smartphone or to provide access to your files to colleagues, you won't need to check for your computers current IP - you just connect to it using the dynamic DNS hostname.
Example 2: Dynamic DNS on a server
You have a VPS (virtual private server) or a dedicated server on which you are connecting to the HMA! Pro VPN service.
Your server has a static IP (e.g. 5.199.4.10) through which you are accessing the server itself and server-software running on it.
Now if you connect to the VPN on your server, it will not be accessible through its normal IP anymore and can only be reached through the VPN IP. Since you don't know the VPN IP before you connect to the VPN or you might get logged out from your server once the VPN connection has been established, you might have some trouble accessing your server. That's where dynamic DNS will help: A dynamic DNS client application is running on your server which updates the dynamic DNS hostname you registered (e.g. user.no-ip.org) every few seconds with your servers current IP.
That means as long as your server is not connected to the VPN, the DNS hostname will point to its normal IP (e.g. 5.199.4.10).
Once you connect to the VPN, the client application will refresh the hostname with the VPN IP (e.g. 184.59.49.120) so that it points there. This ensures that you will always be able to connect to your server, independent of what IP it is currently using and accessible through.You can even set a normal domain to point to the dynamic DNS hostname (using a CNAME DNS entry), so that your domain or subdomain always leads to the correct IP.
We recommend to use the No-IP dynamic DNS service, it's free:
- No-IP (http://www.no-ip.org)
Lists of other dynamic DNS host services can be found here:
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