Troubleshooting a intermittent connection issue we noticed that IIS 8.5 on "Idle connection timeout"(default 120sec) is sending a RST flag to Loadbalancer instead of FIN flag.
Is this is a standard behaviour of IIS to send RST flag on idle timeouts?
"Vendor app" -> "Load Balancer Netscalar" -> "IIS"
The issue we are facing is when IIS sends a RST flag on idle time out to Loadbalancer, the load balancer is not communicating this to the "vendor app" which made the request.
so while the connection b/w LB and IIS is closed, the connection b/w vendor app and LB is still in established state, which seems to be causing intermittent connection issues(Target server failed to respond).