无法在默认端口上建立 DAC 连接。确保 DAC 已启用

Question

当我登录到 Sql-Server 操作系统的远程桌面时，无法使用 SSMS 建立本地DAC 连接。第一个原因是 SQL 浏览器服务关闭。后来，我被指出的第二个原因是“DAC 未激活”错误：

“无法在默认端口上建立 DAC 连接。请确保 DAC 已启用”。

我寻找解决方案。我发现的建议解决方案是启用“RemoteDacEnabled”Facet 属性或运行

sp_configure 'remote admin connections', 1 

这让我想知道，为什么我应该启用REMOTE DacEnabled 属性，以防我想从本地系统连接？我这里的 REMOTE 是不是错了？

MSDN 解释说：

"The connection is only allowed from a client running on the server. No network connections are permitted."

If I HAVE TO logon from local server and NOT over the network, what sense does a REMOTE DAC setting ever make?

EDIT/part of the answer: The main reason for my question was, that I did NOT understand why we have to allow /enable the REMOTEDAC settings just in case we want to establish a LOCAL DAC connection from the server itself (that was what I tried with no luck in the first place).

NOW after giving it more tries I figured out that using...

ServerName.SubDomain.Domain.de

caused this error connecting to DAC while...

ServerName

DOES WORK (without activating the RemoteDac setting).

(Weird about this is that I can connect fine using a "normal" connection with both options)

Root cause was that the FQDN was interpreted to be a remote server and this caused the error above.

However, after I have enabled REMOTEDAC, both options from above work for a DAC, no matter if I try it local on the server or from remote clients.

Answer 1

From Using a Dedicated Administrator Connection:

By default, the connection is only allowed from a client running on the server. Network connections are not permitted unless they are configured by using the sp_configure stored procedure with the remote admin connections option.

From that latter page:

SQL Server provides a dedicated administrator connection (DAC). The DAC lets an administrator access a running server to execute diagnostic functions or Transact-SQL statements, or to troubleshoot problems on the server, even when the server is locked or running in an abnormal state and not responding to a SQL Server Database Engine connection. By default, the DAC is only available from a client on the server. To enable client applications on remote computers to use the DAC, use the remote admin connections option of sp_configure.

I think the page you read is just a little light on the details, that's all.

至于为什么本地DAC 连接可能无法工作，可能是因为您运行的是 SQL Server Express，它需要 TF 7806 才能启用. 另一种可能性是启用的网络协议。