[SOLVED] How to create a fourth (4th) level domain?


is it possible to create a fourth (4th) level subdomain using the web interface?

--> not my real subdomain!
--> already working fine

--> already created but not working

My thehellsite.dedyn.io subdomain gets updated from my OPNsense using DynDNS.
On my OPNsense I have a reverse proxy up and running (HAProxy) that is serving some websites but in order for my reverse proxy to work correctly I would need additional subdomains on my main-subdomain.

What I would like to achieve:
I would like my iot.thehellsite.dedyn.io subdomain to get its IP directly from my thehellsite.dedyn.io subdomain so I don’t “abuse” your servers with a ton of dyndns requests.

Searching the forum I saw a post from @mihi where he is already using a fourth level domain.
Maybe he can tell me how to do that.

Kind Regards

If you create a separate 4th level domain, you will have to enter its DNS records into the 3rd level domain. But you will only need this if the 4th level domain is on a different dedyn account or you need to use the DynDNS API to update it.

For your use case, you don’t need to register the 4th level domain at all (and you have to delete it before you can proceed). Simply edit the DNS records of your already existing 3rd level domain and add some CNAME records pointing to your main domain, i.e

iot CNAME thehellsite.dedyn.io.

(In the post you referred to, I also used CNAME records (the CNAME pointing to GitHub Pages server farm), and I had to use a 4th level domain as it is not possible to have a CNAME at the domain apex (which is the 3rd level in case of dedyn.io, as dedyn.io itself is a “public suffix” where domains are registered below.).


My error was that I put iot.thehellsite.dedyn.io in the “Target hostname” of the cname record and left the “Subname” field blank.
However your explanation totally makes sense and it worked instantly.

Just in case anyone is interested here you can find my example config.
4th-level.3rd-level.dedyn.io now gets resolved to the same IP that 3rd-level.dedyn.io gets resolved to.