| title | Driver and client connectivity support for availability groups | |||
|---|---|---|---|---|
| description | This topic describes considerations for client connectivity to Always On availability groups, including prerequisites, restrictions, and recommendations for client configurations and settings. | |||
| author | MashaMSFT | |||
| ms.author | mathoma | |||
| ms.reviewer | randolphwest | |||
| ms.date | 07/29/2022 | |||
| ms.service | sql | |||
| ms.subservice | availability-groups | |||
| ms.topic | concept-article | |||
| helpviewer_keywords |
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[!INCLUDE SQL Server]
This article describes considerations for client connectivity to Always On availability groups, including prerequisites, restrictions, and recommendations for client configurations and settings.
The section below provides information about [!INCLUDEssHADR] support for client connectivity.
The following table summarizes driver support for [!INCLUDEssHADR]:
| 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 1 | Yes | Yes | Yes | Yes | Yes |
| ADO.NET with .NET Framework 3.5 SP1 with connectivity patch 2 | Yes | Yes | Yes | Yes | Yes |
| Microsoft ODBC Driver 13.1+ for SQL Server | Yes | Yes | Yes | Yes | Yes |
| Microsoft JDBC Driver 4.0+ for SQL Server | Yes | Yes | Yes | Yes | Yes |
| Microsoft OLE DB Driver for SQL Server 3 | Yes | Yes | Yes | Yes | Yes |
1 Download the connectivity patch for ADO .NET with .NET Framework 4.0.
2 Download the connectivity patch for ADO.NET with .NET Framework 3.5 SP1.
3 Download the Microsoft OLE DB Driver for SQL Server.
Important
To connect to an availability group listener, a client must use a TCP connection string.
- Creation and Configuration of Availability Groups (SQL Server)
- Create or Configure an Availability Group Listener (SQL Server)
- 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