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When you try to connect to a Microsoft SQL Server named instance by using a Canonical Name (CNAME), the client receives the following error message, and the connection fails:
SQL Server does not exist or access denied ConnectionOpen (Connect())
This behavior also occurs when you try to connect to a SQL server named instance by using the Hosts (A records).
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft Data Access Components (MDAC) service pack that contains this hotfix.
To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
Date Time Version Size File Name -------------------------------------------------------- 26-Jun-2003 18:39 2000.81.9031.49 61,440 Dbnetlib.dll
Note The installer for this fix is named Q818510_MDAC27_x86.exe.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
A CNAME or canonical name is an alias for a particular TCP/IP address that is defined in DNS (Domain Name System). For example, if the TCP/IP address is 10.10.10.10 and if the real computer name is Server1, you can define a CNAME in DNS that is named Server2 that also resolves to the 10.10.10.10 TCP/IP address. Therefore, with a CNAME, you can have two names that point to the same TCP/IP address.