SQL Server Q&A

Symptoms
The purpose of this article is to help you in the setup or in the troubleshooting of a configuration for a COM+ Application Server or a configuration for an Internet Information Server (IIS) computer that interacts with a clustered server that uses Microsoft Cluster Server (MSCS) that is behind a firewall.
You may have one of the following scenarios: COM+ or IIS computer (client computer)SQL Server clustered that uses MSCSMicrosoft Distributed Transaction Coordinator (MSDTC) as a clustered resource in its own resource group (own name and IP address)Cluster and client computer that are separated by a firewall Certain Internet Protocol (IP) addresses and their corresponding network names must be known by the client computer for MSDTC to work correctly. The client computer can resolve the following names and the following IP addresses by using Domain Name System (DNS), hosts file, or another name resolution method: MSDTC resourceAn instance of SQL Server if the cluster configuration is either active-passive or active-activeCluster Name Certain IP addresses and their corresponding network names must be known by the nodes in the cluster for MSDTC to work correctly. Both nodes in the cluster can resolve the client computer name to an IP address by using DNS, hosts file, or another name resolution method.
Resolution
Additionally, the firewall must be configured to allow bidirectional traffic to occur between the client computer and the cluster. The firewall rules must include the following: The IP network names and the addresses of both physical nodes on the clusterThe SQL Server Instances network names and addressThe client network name and addressesThe child network name and IP resource of the MSDTC Resource Firewall rules must include the range of IP ports that are defined in the registry to allow traffic. See the “References” section.
You may also have to open an additional range of available IP ports as a requirement for the cluster server. See the “References” section for more information.

Symptoms
If you try to connect a clustered named instance of SQL Server through a firewall, and you use only the instance name (for example,SQL_Virtual_Name\Instance_Name) in the connection string, the connection fails and you may receive one of the following error messages:
Error message 1

Specified SQL server not found.
Error message 2

SQL Server does not exist or access denied.If you run a network trace on the server, you can see that the server actually receives the query from the client computer on UDP port 1434 for the virtual server IP address; however, the answer is sent with the physical IP address of the cluster node that is currently running SQL Server.
Resolution
When a client computer connects to a computer that is running a clustered instance SQL Server, if the connection string does not specify the destination TCP port, the client library queries the server on port UDP 1434 to collect information about the instance.
When the server returns the information, the network frame contains the IP address of the physical node instead of the IP address of the virtual server. Depending on the firewall configuration, this network packet may be dropped, and the client may not receive any answer.

Symptoms
After you install a 64-bit version of Microsoft SQL Server 2005 on a 64-bit version of a Microsoft Windows operating system, the 32-bit entries for SQL Native Client Configuration and for SQL Server 2005 Network Configuration appear in SQL Server Configuration Manager.
Resolution
Some tools that are installed together with a 64-bit version of SQL Server 2005 are available only as 32-bit versions. When you install a 64-bit version of SQL Server 2005, the 32-bit versions of the following tools are installed:SQL Server Management StudioSQL Server Configuration ManagerDatabase Engine Tuning AdvisorThe following entries appear in SQL Server Configuration Manager:SQL Server 2005 Network Configuration (32bit)SQL Native Client Configuration (32bit)SQL Server 2005 Network ConfigurationSQL Native Client ConfigurationThe following table contains information about each entry.
Note Client Network Utility (Cliconfg.exe) is available in SQL Server 2000.In SQL Server 2005, the functionality of this tool is included in SQL Server Configuration Manager. However, to address backward compatibility issues, Client Network Utility is included in SQL Server 2005.
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Entry in SQL Server Configuration ManagerVersionResidence of aliases that are created in SQL Server Configuration ManagerCorresponding subkey in the registryApplications that are affected by the protocol settingsAvailability of aliases to applicationsResidence of aliases that are created by Client Network UtilitySQL Native Client Configuration (32bit)32-bitAliases that are created in this entry reside only in this entryHKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\MSSQLServer\Client\ConnectToNot applicableOnly 32-bit applications can use aliases in this entryNot applicableSQL Native Client Configuration64-bitAliases that are created in this entry reside only in this entryHKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\Client\ConnectToNot applicableOnly 64-bit applications can use aliases in this entryResides only in this entrySQL Server 2005 Network Configuration (32bit)32-bitNot applicableHKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\MSSQLServer\Client\SNI9.0Only 32-bit applications are affectedNot applicableNot applicableSQL Server 2005 Network Configuration64-bitNot applicableHKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\Client\SNI9.0Only 64-bit applications are affectedNot applicableNot applicable

Symptoms
When you upgrade an instance of SQL Server to SQL Server 2008, some client-related protocol settings are not automatically applied to the SQL Server 2008 client. For example if you have enabled Secure Socket Layer Encryption (SSL) on a SQL Server 2005 instance either by turning on the Force protocol encryption option in Client Network utility or by using the Properties page of SQL Native Client Configuration in SQL Server configuration manager, the setting is not preserved when you upgrade that instance to SQL Server 2008.
Resolution
This behavior is by design.