A CNAME (Alias) record points to an A (Host) record. One can create multiple CNAME records and point them to an A record.

CNAMEs can only be set for subdomains that are registered with 1&1. If using a CNAME, all DNS(Domain Name System) settings configured through the 1&1 Control Panel will be discarded. A CNAME can be thought of as a kind of pointer for DNS. Instead of specifying DNS settings for a domain in the Control Panel, using a CNAME indicates that the DNS settings for the Subdomain should be exactly the same as the DNS settings for the CNAME address.

Solution

Note: You might need to configure a CNAME record first.

Follow the instructions provided below to move Subdomain from A-Record to CNAME on 1&1 hosting:

1. Log in to the 1&1 Control Panel and select the relevant package.
2. Click Manage Domains from the Domains panel.
   
   
3. Locate the domain that contains the subdomain one wants to modify and then click Manage Subdomains.
   
   
   
4. Check the box next to the Subdomain to select it.
5. Click Edit DNS Settings from the Subdomain Settings drop-down menu.
   
   
   
6. Select the CNAME option.
7. Enter the CNAME address cms.mobileapphelper.com in the Alias text box
8. Check the box to acknowledge that you are aware all current DNS settings will be disabled by using a CNAME instead.
   
9. Click Save button to continue.