Currently I am using local database for authentication on my pfsense. I know that Cisco's IOS has backup authentication methods for the cases when primary one fails. You can even not to authenticate at all if all servers fail. I want to use AD user base to organize the user control, but here is a question, what will happen when AD fails, can pfsense jump to local database?
By default, pfSense will try a local account – after a long delay until the connection times out.
(There were fixes regarding this in 2.4-git, but in current release versions everything will be slow.)