What is a common authentication method besides built-in accounts in Portal for ArcGIS?

LDAP, or Lightweight Directory Access Protocol, is indeed a common authentication method used alongside built-in accounts in Portal for ArcGIS. It allows organizations to integrate their existing directory services for user authentication. This method is particularly beneficial for enterprises that manage large numbers of users, as it centralizes authentication and enables easier user management.

Using LDAP, organizations can authenticate users against an existing directory, such as Microsoft Active Directory or OpenLDAP. This approach enhances security, as passwords are managed centrally and can be subjected to the organization’s existing policies and procedures.

The other options do not serve the same purpose as authentication methods. Simple password protection typically involves lesser security measures and is not sufficient for larger organizations. Dynamic link generation does not provide a way to authenticate users but instead focuses on how links to resources are created. Default guest access allows users to access certain capabilities without authentication, which doesn't align with the principles of secure user authentication that LDAP offers. Thus, LDAP stands out as the correct choice for a common alternative authentication method in this context.