April 4, 2018 at 9:03 am
We are running SQL Server 2014 Web Edition. The DAC has been enabled, remote connections are enabled, and the Browser Service is running, but it is still not possible to connect to the DAC either through a new SSMS window (prefixing the server name with "Admin:") or via SQLCMD. Please help!
SSMS Error:
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 43 - An error occurred while obtaining the dedicated administrator connection (DAC) port. Make sure that SQL Browser is running, or check the error log for the port number) (Microsoft SQL Server, Error: -1)
SQLCMD Error:
Sqlcmd: Error: Microsoft ODBC Driver 11 for SQL Server : SQL Server Network Interfaces: An error occurred while obtaining the dedicated administrator connection (DAC) port. Make sure that SQL Browser is running, or check the error log for the port number [xFFFFFFFF]. Sqlcmd: Error: Microsoft ODBC Driver 11 for SQL Server : Login timeout expired. Sqlcmd: Error: Microsoft ODBC Driver 11 for SQL Server : A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online.
SQL Server Error log:
Dedicated admin connection support was established for listening remotely on port 1434.
Version:
Microsoft SQL Server 2014 (SP2-CU10-GDR) (KB4052725) - 12.0.5571.0 (X64)
Jan 10 2018 15:52:08
Copyright (c) Microsoft Corporation
Web Edition (64-bit) on Windows NT 6.3 <X64> (Build 9600: ) (Hypervisor)
April 4, 2018 at 9:14 am
zoggling - Wednesday, April 4, 2018 9:03 AMWe are running SQL Server 2014 Web Edition. The DAC has been enabled, remote connections are enabled, and the Browser Service is running, but it is still not possible to connect to the DAC either through a new SSMS window (prefixing the server name with "Admin:") or via SQLCMD. Please help!SSMS Error:
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 43 - An error occurred while obtaining the dedicated administrator connection (DAC) port. Make sure that SQL Browser is running, or check the error log for the port number) (Microsoft SQL Server, Error: -1)SQLCMD Error:
Sqlcmd: Error: Microsoft ODBC Driver 11 for SQL Server : SQL Server Network Interfaces: An error occurred while obtaining the dedicated administrator connection (DAC) port. Make sure that SQL Browser is running, or check the error log for the port number [xFFFFFFFF]. Sqlcmd: Error: Microsoft ODBC Driver 11 for SQL Server : Login timeout expired. Sqlcmd: Error: Microsoft ODBC Driver 11 for SQL Server : A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online.SQL Server Error log:
Dedicated admin connection support was established for listening remotely on port 1434.Version:
Microsoft SQL Server 2014 (SP2-CU10-GDR) (KB4052725) - 12.0.5571.0 (X64)
Jan 10 2018 15:52:08
Copyright (c) Microsoft Corporation
Web Edition (64-bit) on Windows NT 6.3 <X64> (Build 9600: ) (Hypervisor)
Have a look at this!
😎
April 4, 2018 at 9:18 am
Further information:
It turns out these errors only occur when attempting to connect to a given instance via the DAC from a different database server on the same network. We can connect without using the DAC fine. And the DAC connection is not being used by anything else, so something isn't quite right here.
Obviously we want to avoid having to RDP direct to the database server in order to connect to its default instance using the DAC either via SQLCMD or SSMS! Surely it should be possible to connect from a different server?
April 4, 2018 at 10:40 am
zoggling - Wednesday, April 4, 2018 9:18 AMFurther information:
It turns out these errors only occur when attempting to connect to a given instance via the DAC from a different database server on the same network. We can connect without using the DAC fine. And the DAC connection is not being used by anything else, so something isn't quite right here.
Obviously we want to avoid having to RDP direct to the database server in order to connect to its default instance using the DAC either via SQLCMD or SSMS! Surely it should be possible to connect from a different server?
You need to enable remote admin connections -
remote admin connections Server Configuration Option
Sue
April 5, 2018 at 2:41 am
Hi Sue, yes I can confirm that this had already been enabled.
Configuration option 'remote admin connections' changed from 1 to 1. Run the RECONFIGURE statement to install.
Unfortunately we are still unable to connect to the DAC on server 1 from server 2.
April 5, 2018 at 3:09 am
Hi,
are you working with (local) firewalls?
default port sql server engine is 1433, but DAC port is 1434
Are you able to telnet this port from server2 to server1?
kind regards,
Andreas
April 5, 2018 at 3:19 am
andreas.kreuzberg - Thursday, April 5, 2018 3:09 AMHi,
are you working with (local) firewalls?
default port sql server engine is 1433, but DAC port is 1434
Are you able to telnet this port from server2 to server1?
kind regards,
Andreas
Further, is the SQL Server Browser Service port, UDP 1434 (default) open?
😎
April 5, 2018 at 4:05 am
It appears at present that TCP port 1434 is being blocked by our inter-data centre firewalls. This protocol/port has already been configured in the local firewalls. We are just waiting to see if this fixes the issue.
Eirikur - UDP port 1434 does not appear to be required to connect via the DAC if we attempt to connect from one server to another within the same data centre, possibly because we do not have any named instances in this environment (the SQL Server Browser services have since been disabled!)
And what's with the "Failed to connect to server ADMIN:<server>\<namedinstance>" error when connecting to the DAC via SSMS?! :blink:
April 5, 2018 at 7:11 am
zoggling - Thursday, April 5, 2018 4:05 AMIt appears at present that TCP port 1434 is being blocked by our inter-data centre firewalls. This protocol/port has already been configured in the local firewalls. We are just waiting to see if this fixes the issue.Eirikur - UDP port 1434 does not appear to be required to connect via the DAC if we attempt to connect from one server to another within the same data centre, possibly because we do not have any named instances in this environment (the SQL Server Browser services have since been disabled!)
And what's with the "Failed to connect to server ADMIN:<server>\<namedinstance>" error when connecting to the DAC via SSMS?! :blink:
The Browser can be needed for connections to the DAC. It's not just named instances but if the instance is listening on a non-default port it is required.
SQL Server Browser Service
You say you don't have any named instances but the error you posted: "Failed to connect to server ADMIN:<server>\<namedinstance>"
which really seems to be a named instance.
Nonetheless, if you are getting an error message box that is exactly "Failed to connect to server ADMIN:<server>\<namedinstance>" and nothing else, you may want to try just dismissing the message box so you connect and then checking your status bar. There are times you can get that message box and it really means nothing and you actually are connected with the DAC. You will see ADMIN:ServerName on the status bar for the connection.
Sue
April 5, 2018 at 7:38 am
Hi Sue, thank you for the clarification regarding the Browser Service, that's really helpful. I modified the error message to add <namedinstance> for completeness, apologies if it was misleading. Yes I could see the connection had been established in the status bar, it appears to be a rather confusing message to display if the connection has succeeded!
Will update on the main issue once confirmed.
April 6, 2018 at 7:35 am
TCP port 1434 was being blocked by our inter-data centre firewalls. The issue has now been fixed. Thanks to all for your help!
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