Log in to your 1&1 Control Panel and select the relevant package.
Click on Domains in your control panel
Select the domain you'd like to change name servers for
Click "Advanced Settings"
Select "Edit DNS settings" , then "Other Name servers"
- Enter the first name server address into the Primary name server text box.
- Select My secondary name server from the Secondary name server drop-down box to add a second address.
- Enter the second name server address into the 1st secondary name server text box.
- Click on Save to proceed.
You may add a third and forth name server address if necessary however only two are required.
All DNS changes may take up to 72 hours to be fully updated and recognised by all servers/computers on the Internet.