After successful upgrade of our Test Enterprise environment to 10.7.1, we are planning the upgrade of our Internal Production & External Production environments. What are best practices to handle access to public web apps during the upgrade/downtime process? If we are using a redirect link "System is down for maintenance" for our external portal and federated server, we will not be able to test web adaptor after reinstalling and configuration, we would only be able to use the local URL to access Portal Admin or Server Manager/Admin. Also, unless I am missing something, I don't think that we would be able to access our Portal home page and test the web applications without the webadaptor link.
Is there a recommended way to inform GIS system is down for maintenance message during system upgrade?