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Situation: I believe that multiple port 1433 can be implemented as long as the IP address are all unique.

I’ve created SQL Server 2008 R2 SP1 clustered virtual instance on top of my Windows Server 2008 R2 SP1 Enterprise MSCS, one instance is working fine and I can perform:

C:\telnet SQLClustername-instance1 1433


However with the other instance I cannot perform the above command and it is not accessible at all ? pinging the SQLClustername-instance2 is fine and reply back, when I do the following command:

C:\netstat –ano | find /I “1433”

I cannot see the SQLClustername-instance2 IP address with port 1433 listening ?

Any assistance would be greatly appreciated.


share|improve this question
I'm not sure 2 instances can share the same port, but that aside for a moment, I think the easy thing to do first is verify what ports each instance is running on. Use SSMS and try connecting but use IP,Port# instead of name. Then look at @@SERVERNAME or one of the SERVERPROPERTY functions and see what instance you're on. Attacking this from the other angle, you could connect by instance name and then run this query to see what port SQL is listening on: "select distinct local_tcp_port from sys.dm_exec_connections where local_tcp_port is not null" – Henry Lee Apr 10 '12 at 14:16
Are the instances in separate subnets? – Thomas Stringer Apr 10 '12 at 14:38
Hi, so in this case there can be only one instance listening on port 1433 ? From the SQL configuration manager, the instance2 ip address it is set 0 as dynamic port. My BiztalkServer 2010 cannot somehow talk to this instance2? So should I make it explicitly 1433 instead of 0? – Server System Specialist Apr 10 '12 at 22:16
up vote 1 down vote accepted

Does the SQL Server instance installed on the cluster resource named SQLclustername-instance2 listen on port 1433? If you installed a named instance then is very likely using dynamic ports. See Configure a Server to Listen on a Specific TCP Port.

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Thanks for the advice mate, so after the changes, where should I do the restart since this is clustered SQL server ? – Server System Specialist Apr 11 '12 at 2:34
How to: Start an Instance of SQL Server. Applies to cluster instances as well. – Remus Rusanu Apr 11 '12 at 5:52
Thanks Remus it works :-) – Server System Specialist Apr 11 '12 at 10:09

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