Failed to Load Group : BizTalkMgmtDB : Issue while opening BizTalk administration console

We had two BizTalk servers added in a group and it is connecting to remote external sql server. Every thing was going fine.. life was coformtable.. until one fine day recieve a email marked Urgent and Subject :
with these two images.

One node of BizTalk Group was working fine and it was really a big relief as we can easily rule out any possible issue realted to SQL server.
So the problem was with the other node and there were numerous BizTalk errors logged by Host Instances, where host instance is trying to start but BizTalk is not able to make connection with the sql server.
Also, in Secuity log there were many audit failures of Windows filtering service.
As our BizTalk most instance were trying to establish the connection with SQL server but al incoming data packets were filtered by this service.Therefore, neither BizTalk Host Instances or BizTalk Administrator Console is able to connect to the SQL Server.



So following are the checklist:
1. Ping SQL server to verify if server is resolved properly.
2. Verify the name of SQL instance where BizTalkMgmtDB is place, there shouldn't be any typo mistake
3. SQL Server is running(not in my list but adding for the completion of blog)
4. Appropiate port (in this case UDP 1434) should be added in exception list or disable firewall(but definately check with server admin before disabling)

Following it the link(which saved my a$$): http://blogs.msdn.com/b/sql_protocols/archive/2007/05/13/sql-network-interfaces-error-26-error-locating-server-instance-specified.aspx


Good Luck :)