We are using different version of IE in our company, from 8 to 10 I believe. Our pac file is configured to hand out the VIP of our hardware load balancers for the proxy server. We also have a second VIP (another cluster of load balancers) as the backup proxy server which is in our pac file as the backup.
If I am surfing and using the first proxy server and my web gateways die, how long does it take before IE determines that the proxy server is dead and then moves onto trying the second proxy server?
It could take 30 seconds and up till the browser switches the connection. We tested it last year and decided to have the VIPs every time running. So, we have four VIPs at one LB-Cluster (4 nodes). With this config three LBs could be "out of order", but all VIPs are online.