HTTP Error 503. The service is unavailable
- by user1671639
I'm struggling to setup the environment in IIS8, I searched a lot but couldn't find a right solution.  
I checked the error logs, but no idea. 
  C:\Windows\System32\LogFiles\HTTPERR
  
  
  2013-10-09 09:28:39 192.168.43.205 60172 192.168.43.205 80 HTTP/1.1
  GET / 503 2 AppOffline qa.hti.local
  2013-10-09 09:28:39 192.168.43.205 60192 192.168.43.205 80 HTTP/1.1
  GET /favicon.ico 503 2 AppOffline qa.hti.local
  
Then in Event Viewer:
  WARNINGS:
  
  
  A listener channel for protocol 'http' in worker process '11188'
  serving application pool 'qa.hti.local' reported a listener channel
  failure.  The data field contains the error number.
  A listener channel for protocol 'http' in worker process '7492'
  serving application pool 'qa.hti.local' reported a listener channel
  failure.  The data field contains the error number.
  A listener channel for protocol 'http' in worker process '9088'
  serving application pool 'qa.hti.local' reported a listener channel
  failure.  The data field contains the error number.
  A listener channel for protocol 'http' in worker process '9964'
  serving application pool 'qa.hti.local' reported a listener channel
  failure.  The data field contains the error number.
  A listener channel for protocol 'http' in worker process '7716'
  serving application pool 'qa.hti.local' reported a listener channel
  failure.  The data field contains the error number.
  
I don't understand what the warning means.
  ERROR: Application pool 'qa.hti.local' is being automatically disabled due to a series of failures in the process(es) serving that
  application pool.
Note: I learned that consecutive 5 failures leads to APP Pool crash, and this can increased.  I also tried increasing this but no success.
OS: Windows server 2012
IIS Version: 8
Please share your thoughts.