Health Check for Stateless API app

[Reward]

Hi,

I have a couple of questions in regard to monitoring the health / state of our F5 Big IP (LTM module) pools and detecting Server failures in those pools.

One of the pools serves are stateless API - so I have been told Round Robin would be the best load balancing method for this particular App.

One of the WEB servers crashed yesterday and the F5 still kept sending live traffic to the node as it was still in the pool.

1. How can you force a server Offline mode - if the server is un-responsive or showing 404 / 500 errors?
2. Do I need to add some iRules to the Pools to resolve?

Any advise would be very much appreciated.

Thanks.