If you have BIG-IQ in your environment to help manage/monitor your applications then let me help understand how to use some cool features of BIG-IQ.

Many times you have several F5's in your environment and trying to identify what F5 has the application you need to troubleshoot is kind of a pain in the butt unless you have BIG-IQ.

First thing I do is if someone says they have an issue with their application is I ask for the FQDN or the URL that is having issues.

Next thing I do is go to BIG-IQ and click on the Configuration Tab then click on Virtual Servers and you get a screen like the one below

You can enter the fqdn in the filter box on the right and if that doesn't work because the name of the virtual server may differ, go to your command prompt and do a dig on the FQDN to get the IP Address and come back to BIG-IQ and enter the IP Address in the Filter box on the right.

What if you get nothing still?

Then a few things could be happening

1. Maybe there application doesn't go through the F5
2. BIG-IQ is only up to date if the application was deployed via JSON/AS3 and for those legacy apps that didn't use JSON/AS3 to deploy, under the Devices Tab you must click those legacy boxes and click import on the services to keep the BIG-IQ database up to date.