Always On Client Connectivity (SQL Server)
This topic describes considerations for client connectivity to AlwaysOn Availability Groups, including prerequisites, restrictions, and recommendations for client configurations and settings.
Client Connectivity Support
The section below provides information about Always On Availability Groups support for client connectivity.
Driver Support
The following table summarizes driver support for Always On Availability Groups:
| Driver | Multi-Subnet Failover | Application Intent | Read-Only Routing | Multi-Subnet Failover: Faster Single Subnet Endpoint Failover | Multi-Subnet Failover: Named Instance Resolution For SQL Clustered Instances |
|---|---|---|---|---|---|
| SQL Native Client 11.0 ODBC | Yes | Yes | Yes | Yes | Yes |
| SQL Native Client 11.0 OLEDB | No | Yes | Yes | No | No |
| ADO.NET with .NET Framework 4.0 with connectivity patch***** | Yes | Yes | Yes | Yes | Yes |
| ADO.NET with .NET Framework 3.5 SP1 with connectivity patch ** | Yes | Yes | Yes | Yes | Yes |
| Microsoft JDBC driver 4.0 for SQL Server | Yes | Yes | Yes | Yes | Yes |
* Download the connectivity patch for ADO .NET with .NET Framework 4.0: https://support.microsoft.com/kb/2600211.
** Download the connectivity patch for ADO.NET with .NET Framework 3.5 SP1: https://support.microsoft.com/kb/2654347.
Important
To connect to an availability group listener, a client must use a TCP connection string.
Related Tasks
Creation and Configuration of Availability Groups (SQL Server)
Create or Configure an Availability Group Listener (SQL Server)
See Also
Overview of AlwaysOn Availability Groups (SQL Server)
Failover Clustering and AlwaysOn Availability Groups (SQL Server)
Prerequisites, Restrictions, and Recommendations for AlwaysOn Availability Groups (SQL Server)
Availability Group Listeners, Client Connectivity, and Application Failover (SQL Server)
About Client Connection Access to Availability Replicas (SQL Server)
Microsoft SQL Server AlwaysOn Solutions Guide for High Availability and Disaster Recovery
SQL Server AlwaysOn Team Blog: The official SQL Server AlwaysOn Team Blog
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Slow failover operation if no router exists between the cluster and an application server