The A record is the DNS record that holds which IP address the domain should point to. By default, this will point to the IP address for your 1&1 WebHosting package however you can always change this so that the domain points to a different IP address. You can only edit the A record of a domain that is hosted with 1&1.
In this article you will find out how to edit an A Record via the 1&1 Control Panel.
Select Other IP address and enter IPv4 and optionally the IPv6 address into the provided text boxes.
Click the Save button when finished.