What does port 4774 do?

Question

Hi,

I've been working on a SQL 2008 R2 (2-node) HA cluster running a DB for Lync 2010. I ran into problems when setting up Lync; DB communication from remote hosts was not possible. Aside of that: When the DB resource was running on lets say 'node A', I could never connect to the DB from 'node B' when using HA cluster name(+instance name). When moving the resource to node B, the same problem would appear on node A. In all cases, the node holding the resource would always be able to successfuly connect to the DB using cluster name+instance name.

After much troubleshooting I found: this link on MSDN where someone talks about a similar problem involving remote connections and somewhere in this problem description he states that port 4774 was not responding on telnet requests. In our setup, port 4774 had not appeared, thus wasn't opened in the Windows firewall on the SQL nodes. After opening the port on node B, node A would successfuly connect on the DB using cluster name+instance name. Moving the resource to node A and trying to connect from node B would be unsuccessful. However, opening the tcp port 4774 on node A would allow for successful connections.

I haven't found a viable explaination as to why this port suddenly seemed to fix my issue. Is there anyone who can help me in this case? Point me to a link or something?

Many thanks!

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Answer 1

TCP & UDP Port 4774 Information

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Answer 2

Anuragsh,

Thanks for the reply.

However, I've seen that site before, as I stated I already did a thorough internet search and I can't use that explaination.

Cheers

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Answer 3

HI jeroen,

Is this a active/Active cluster ?

If it is Active/Passive cluster the behavior is expected. Only active node takes control of shared resources and allowed for remote access.

If you are still able to connect by opening port 4774, it may be hard work to prove that you are still talking to your Active node. Behind the scene shared disks sync with each other.

Try with SQL-profiler running before close and after close for the same action and see if you can find some difference.

thanks

kumar

Answer 4

Windows Firewall on Windows Server 2008 helps prevent unauthorized access to computer resources. However, if the firewall is configured incorrectly, attempts to connect to an instance of Microsoft SQL Server may be blocked. To access an instance of SQL Server that is behind the firewall, you must configure the firewall on the computer that is running SQL Server.

http://support.microsoft.com/kb/968872

Answer 5

Hi

you can click on below :

http://www.pc-library.com/ports/tcp-udp-port/4774/

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