A user has hosted an application on EC2 instances. The EC2 instances are configured with ELB and Auto Scaling. The
application server session time out is 2 hours. The user wants to configure connection draining to ensure that all in-flight
requests are supported by ELB even though the instance is being deregistered. What time out period should the user
specify for connection draining?

A.
5 minutes

B.
1 hour

C.
30 minutes

D.
2 hours

Explanation:
When you enable connection draining, you can specify a maximum time for the load balancer to keep connections alive
before reporting the instance as de-registered. The maximum timeout value can be set between 1 and 3,600 seconds
(the default is 300 seconds). When the maximum time limit is reached, the load balancer forcibly closes connections to
the de-registering instance.
http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/config-conn-drain.html