domain

The domain name for the domain that hosts the sign-up and sign-in pages for your application. For example: auth.example.com . If you're using a prefix domain, this field denotes the first part of the domain before .auth.[region].amazoncognito.com . This string can include only lowercase letters, numbers, and hyphens. Don't use a hyphen for the first or last character. Use periods to separate subdomain names.