Exchange 2010 Active sync (Access mail in Mobile issues)

Hi

In my organisation Exchange server 2010 SP1 are deployed before six months itself & we accessed mail in mobile through active sync initially. Recently(one month back) we facing problem in accessing mail in active sync. 

While we tried to configure mailbox in mobile through Active sync it shows error "Server is not available"

Initially i don't have autodiscover record in internal dns as well as public dns. Right now i had on both.

Pls see the error which i received in testconnectivity.microsoft.com

The Microsoft Connectivity Analyzer is checking the host autodiscover.astraglobal.co for an HTTP redirect to the Autodiscover service.
	The Microsoft Connectivity Analyzer failed to get an HTTP redirect response for Autodiscover.
	Additional Details   An HTTP 403 forbidden response was received. The response appears to have come from Unknown. Body of the response: You do not have permission to view this directory or page. Headers received: Content-Length: 58 Content-Type: text/html Date: Mon, 11 Nov 2013 07:02:55 GMT Server: Microsoft-IIS/7.5 X-Powered-By: ASP.NET Elapsed Time: 509 ms.

Kindly help me 

Thanks