Always On Client Connectivity (SQL Server)


Published: May 13, 2016

Updated: May 17, 2016

THIS TOPIC APPLIES TO: yesSQL Server (starting with 2016)noAzure SQL DatabasenoAzure SQL Data Warehouse noParallel Data Warehouse

This topic describes considerations for client connectivity to Always On Availability Groups, including prerequisites, restrictions, and recommendations for client configurations and settings.

In this Topic:

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:

DriverMulti-Subnet FailoverApplication IntentRead-Only RoutingMulti-Subnet Failover: Faster Single Subnet Endpoint FailoverMulti-Subnet Failover: Named Instance Resolution For SQL Clustered Instances
SQL Native Client 11.0 ODBCYesYesYesYesYes
SQL Native Client 11.0 OLEDBNoYesYesNoNo
ADO.NET with .NET Framework 4.0 with connectivity patch*YesYesYesYesYes
ADO.NET with .NET Framework 3.5 SP1 with connectivity patch**YesYesYesYesYes
Microsoft JDBC driver 4.0 for SQL ServerYesYesYesYesYes

*Download the connectivity patch for ADO .NET with .NET Framework 4.0:

**Download the connectivity patch for ADO.NET with .NET Framework 3.5 SP1:

System_CAPS_ICON_important.jpg Important

To connect to an availability group listener, a client must use a TCP connection string.

Overview of Always On Availability Groups (SQL Server)
Failover Clustering and Always On Availability Groups (SQL Server)
Prerequisites, Restrictions, and Recommendations for Always On 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 Always On Solutions Guide for High Availability and Disaster Recovery
SQL Server Always On Team Blog: The official SQL Server Always On Team Blog
A long time delay occurs when you reconnect an IPSec connection from a computer that is running Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7, or Windows Server 2008 R2
The Cluster service takes about 30 seconds to fail over IPv6 IP addresses in Windows Server 2008 R2
Slow failover operation if no router exists between the cluster and an application server

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