Which of the following Azure Application Gateway features can protect web applications against SQL injection attacks?

You have a back-end pool made up of four Azure infrastructure as a service (IaaS) virtual machines. Occasionally, one or more of these virtual machines might become temporarily unresponsive. You want to ensure that Application Gateway doesn't forward traffic to an unresponsive virtual machine, even if you're unaware that a problem exists. Which Application Gateway feature can prevent traffic from forwarding to an unresponsive virtual machine?

You have a back-end pool made up of eight Azure IaaS virtual machines. You need to install a new framework on each of these virtual machines. You don't want the virtual machine to participate in the back-end pool while you do this maintenance operation. You want to stop new connections from occurring on the VM that you're doing maintenance on, and you also want to allow any existing connections that are present to complete naturally. Which of the following Azure Application Gateway features can you use to accomplish this goal?