1. User tries to access the App
2. Apache server should redirect the request to 2 different Apps based on the following condition
2.1 If the request comes from 192.168.10.XXX series it should redirect to App1
2.2 If the request comes from 192.168.100.XXX series it should redirect to App2
2.3 If any one App is down the Apache server should send the reuqest to the running App
2.3.1 If a request is coming from 192.168.100.XXX series and App2 is down then the Apache server should
redirect to App1
It would be better to route requests based on actual loads rather than simply on which source network address they came from. Otherwise, one server can end up swamped while the other is idle, and since "swamped" isn't the same thing as "down", your fallback case wouldn't apply.
However, you should be able to employ Apache's mod_rewrite rules to rewrite the incoming URLs based on the source network.
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