You can configure the firewall to use
External
Authentication Services for authenticating administrators
who access the firewall or Panorama and end users who access services
or applications through Authentication Portal. To ensure that the
firewall does not waste resources by continuously trying to reach
an authentication server that is unreachable, you can set a timeout
interval after which the firewall stops trying to connect. You set
the timeout in the server profiles that define how the firewall
connects to the authentication servers. When choosing timeout values,
your goal is to strike a balance between the need to conserve firewall
resources and to account for normal network delays that affect how
quickly authentication servers respond to the firewall.