Name Based Virtual Hosting irule efficiency

I have put in place the irule along with the custom health monitor for each application. We are testing out two applications and the two that applications that are using the monitor are working and directing traffic with and without the irule.

Here is the setup:

pool test1.pool nodes 10.1.1.1 10.1.1.2 monitor GET /f5-monitor/f5-monitor.jsp HTTP/1.1\r\nHost: test1.com\r\nConnection: Close\r\n\r\n

pool test2.pool nodes 10.1.1.1 10.1.1.2 monitor GET /f5-monitor/f5-monitor.jsp HTTP/1.1\r\nHost: test2.com\r\nConnection: Close\r\n\r\n

I am able to get to test1.com and test2 with and without the use of the irule or data groups. How's this happening since the nodes are using the same pair of apache servers that are serving up the host header information and properly being routed to each application?

Thanks