How do I set up DuckDNS with my Linode?

I'm trying to use my duckdns domain in your DNS manager, but I keep getting the message "A domain like example.duckdns.org already exists in our database."

This error means that someone is already using that domain on their account, and this message will show up any time you try to define a subdomain of duckdns.org. You'll either need to have your own custom domain to create records, or reach out to our support team to file a domain dispute. This would require proof of ownership of duckdns.org, so chances are you won't be able to as a regular user of their service.

Do you guys not support duckdns?

The good news is, you don't need to be able to create domain records to use duckdns at all. They host the records themselves, and it only takes a few minutes to set this up on your Linode.

First, you'll want to sign up or login at duckdns.org to create the subdomain you'd like to use. After that, update the IPv4 and IPv6 fields on that page with your Linode network addresses. You can view all your Linode networking information by clicking on your Linode in Cloud Manager and then selecting the "Networking" tab. Copy those addresses into your duckdns domain settings and hit update.

Before your subdomain will actually work, you'll need to install duckdns on your Linode. To do this, log into your Linode console over SSH, or using Lish. Be sure that you are using a user with sudo privileges.

Then, just use the commands and guidance in their linux cron installation guide (be sure to follow all directions). After you install duckdns on the Linode, you should be able to start using your subdomain right away. When I set up a quick test domain it was pretty much instant, and didn't seem to have any propagation time.

One thing to note about the installation guide above, the public page I linked mentions "you must change your token and domain to be the one you want to update" in the section where you edit the duck.sh file. If you are logged in, the guide will actually automatically update to include your domain and unique token. It never hurts to double check, but as long as you're logged in you should be able to copy that without needing to edit anything.