Customer requirement: during a monthly change and maintenance window, all visitors / users accessing websites / web applications should be redirected to a maintenance page. The timeframe is specified as “first Friday every month between 1pm and 11pm”.
NetScaler solution: create responder action delivering redirect to maintenance page. Create responder policy requesting this action and bind it globally. Use the following expression:
SYS.TIME.WEEKDAY.EQ(5) && SYS.TIME.DAY.LE(7) && SYS.TIME.HOURS.BETWEEN(13,22)
Last but not least: make sure timezone is set correctly, NTP is configured, enabled and working.