Subdomains do not require registration since they are created for existing domains. For each 1&1 IONOS Contract, you can create up to 10,000 subdomains. This can be useful, for example, if you want to structure your website content.
Use the following button to create a subdomain for an existing domain. After selecting a domain, you will be shown the corresponding option.
Please Note: A recently deleted subdomain should not be recreated within 2 hours of the deletion.
Naming the Subdomain
The name of the subdomain comes before the domain name and can be anything you choose (provided the characters used are allowed). Popular subdomain include, for example, shop.yourdomain.com or blog.yourdomain.com. It is not necessary to precede your subdomains with an additional www since www is itself already a subdomain.
The subdomain www.yourdomain.com is automatically created for all of your domains and functions the same as the actual domain by default. If you would like to specify another use for it, you can always manually create a www.yourdomain.com and customize it to meet your needs.
You can find more information about the structure and length of subdomains and permitted characters in this article.
Configuring a CNAME Record for a Subdomain
After creating the subdomain, you can configure a CNAME record for the subdomain if necessary.
Please Note: Subdomains that start with an underscore cannot be created with 1&1 IONOS. However, some external service providers, such as MailChimp, require the configuration of a CNAME record for a host beginning with an underscore.
If this is the case for you, please see the article Creating a CNAME Record for a Host Name that Begins with an Underscore.