A CNAME record is an alias for a subdomain. When you configure a CNAME record for a subdomain, DNS queries are no longer sent for the subdomain but for the domain or subdomain specified in the CNAME record to the appropriate name server.
You can add a CNAME record to your subdomain in the Domains section of the Control Panel. The IONOS name servers must also be used at the time for these changes to take any effect.
While it is technically possible to add a CNAME record to your root domain, this is widely known to be a bad DNS practice for a number of reasons and should be avoided.
Additionally, the domain or subdomain specified in the CNAME record must be known to the target or web server so that the requests can be processed correctly by the web server.
If the domain or subdomain specified in the CNAME record is not known to the web server, we recommend that you set up domain forwarding. The same applies if you want to forward the main domain to another domain.
You can find out how to forward a domain to another domain here.
Configuring the CNAME Record
You can configure the CNAME record right in the Domains & SSL section of the Control Panel.
Log in to IONOS and go to the Domains & SSL section.
Next to the desired domain, click on thegear symbol under Actions and select Manage Subdomains.
Next to the desired subdomain, click on the gear symbol under Actions and select DNS.
Click ADD RECORD and select CNAME.
Enter the desired subdomain in the Hostname field. Examples: www or shop
In the Point to field, type the desired entry (alias), specifying the Full Qualified Hostname. This is given without the part http:// or https:// - such as example.com.
Optional: Select the desired TTL.
Your changes are effective at IONOS immediately. However, it can take up to an hour for the change to take effect everywhere due to the decentralized structure of the Domain Name System.