How do I test my IIS failover

The health monitor connections are not included with the pool and virtual server statistics. Your pool will have a "green" status when the health monitor is working correctly. A list of health monitor statuses can be found here. A member will take connections once marked as healthy, and for simple configurations, at least one member needs to be marked as health for the virtual server to take connections. What error do you see when you browse to your test site? Another useful tool on the big-ip is tcpdump; try a simple capture like "tcpdump -i 0.0 port 80 and host " to verify web requests are making it to your virtual server address.