Load balance on App Server Set up

All,

I have a question on load balance on PS app server. I know we configure JOLT failover on PIA side. What I don't quite understand is that under PeopleTools --> Integration Broker --> Configuration --> Gateways, then go to "Gateway Setup Properties", there you set up the "Gateway Default App. Server" and PeopleSoft Nodes, both require specifying an application server url. My question is how the setting here work during a failover?

For example, I have 2 app servers. So in PIA, I set it to go to App server 1 first and then fail over to app server 2. In the "Gateway Default App. Server", i can only set it to 1 of them, let's say I put app server 1 there.