SQL server error 11001 occurs when the SQL Server can’t be found on Network.

This happens if the IP address is not reachable or the TCP port number is either not open or is not the correct port number or is blocked by a firewall

Here at Bobcares, we have seen several such SQL related issues as part of our Server Management Services for web hosts and online service providers.

Today we’ll take a look at the cause for this error and how to fix it.

Why does SQL server error 11001 occur

Now let’s look into what causes this error to occur

1. This error mainly occurs when the SQL Server client can’t connect to the server. This may happen when the client cannot resolve the name of the server or the name of the server is incorrect.

2. If we want to access a SQL server beyond a local area network then the connection must pass through one or more routers and at least one Proxy/Firewall. Sometimes, the Firewall and/or Proxy may not allow SQL Server to be accessed from an external location.

For instance, the error appears as below.

How we resolve SQL server error 11001

Here are the steps that our Support Engineers provide to our customers to follow to fix this error.

1. Enter the correct server name on the client such that you can resolve the name of the server from the client. Also, to check the TCP/IP name resolution, we suggest using the ping command in the Windows operating system.

Also, make sure you are using the correct instance name. When connecting to a default instance, machinename is the best representative for the instance name and when connecting to a named instance such as sqlexpress, we suggest specifying the instancename as follows: machinename\instancename.

Here, enter the SQL Server instance name for instancename.

Also, check that the SQL Server is in the network. Use the command SQLCMD -L to retrieve the list of SQL Servers installed in the network.

NOTE: This will only return SQL Servers if the SQL Server Browser service is running.

2. We suggest running netsvrcn.exe using command prompt as an Administrator on the ‘Server’ running the MSDE Database.

3. Enable TCP/IP and Named Pipes protocol

Check the TCP/IP and Named Pipes protocols and port. First, open SQL Server Configuration Manager and check the SQL Server Network Configuration protocols. Named Pipes and TCP/IP protocol must be enabled.

For the TCP/IP protocol, right-click and select properties and then check the TCP/IP communication port. The default port is 1433. However, this can be changed for security purposes if needed.

4. Restart the SQL Server instance.

5. From the firewall using ‘Windows Firewall Advanced Security’, exclude the ports SQL Server normally listens on, for both inbound and outbound rules:

1433 TCP port
1434 UDP port

6. SQL Server Browser service must be running. You can check the browser service status using either SQL Server Configuration Manager or the SC command as follows.

sc query sqlbrowser

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Conclusion

In short, this error occurs when the SQL Server can’t be found on Network. Today, we saw the resolution to this SQL error.