An Auth Code is only needed for .biz .org .info .name domains.
The Auth code (usually 6-16 digits) works just like a password and is used to protect your domain from unauthorised transfers.
If you are the current owner of a domain, you should have received the auth code after you registered/transferred the domain. If you do not know your auth code you will need to contact your current registrar in order to find it out.
If you wish to transfer a .biz .org .info .name domain to iDAQ you will need to know the auth code before a transfer can occur.
Note: An Auth Code is sometimes also known as: Auth key, Authinfo code or an EPP code.