A CNAME record is an alias for a subdomain. If you configure a CNAME record for a subdomain, the DNS queries are sent to the responsible name server for the domain or subdomain specified in the CNAME record instead of for the original subdomain.
You can add a CNAME record in 1&1 IONOS. It can only be configured for a subdomain. You must also be using the 1&1 IONOS name servers.
Creating a Subdomain
If you have not yet created a subdomain, you first have to create one in 1&1 IONOS. If your chosen subdomain is supposed to begin with an underscore, please continue reading here.
Configuring the CNAME Record
To configure a CNAME record for a subdomain, select the subdomain from the My Domains page and click the DNS tab. Then click the Add record button and choose CNAME as the Type, enter the Hostname, the Value and select a TTL. Please be sure to enter the fully-qualified host name. This does not include the http:// or https:// part.