Creating a CNAME Record for a Host Name that Begins with an Underscore

Subdomains that start with an underscore cannot be created at 1&1 IONOS.

Some providers, however, require you to configure a CNAME record for a host that begins with an underscore. This article will show you how to configure such a CNAME record. You have to use the 1&1 IONOS name servers, and you do not need to have previously created a subdomain.

Creating a CNAME Record for a Host Name in 1&1 IONOS

  • Select a domain from the My Domains page and then click the DNS tab.

  • Click Add Record.

  • Select the CNAME item from the Type list and enter the name of the subdomain in the Host Name text box. This does not contain the domain name. Example: If the subdomain is, then the subdomain name is _domainkey.

  • Then in the Value box enter the host name to be saved as the destination in the CNAME record.

  • Select a TTL from the drop-down box and then click Save.


  • The procedure described is only for configuring CNAME records for host names that contain an underscore.

  • Because of the decentralized structure of the domain name system, it can take up to an hour before the change takes effect everywhere.

  • The subdomain you created is stored only in the DNS zone file. It cannot be used with 1&1 IONOS products.