| 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. | |||
| ms.custom | seodec18 | |||
| ms.date | 07/28/2020 | |||
| ms.prod | sql | |||
| ms.reviewer | ||||
| ms.technology | availability-groups | |||
| ms.topic | conceptual | |||
| helpviewer_keywords |
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| ms.assetid | b456448d-1757-48c8-8bbb-2d1c2d6d61e9 | |||
| author | cawrites | |||
| ms.author | chadam |
[!INCLUDE SQL Server]
This topic 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.
Driver Support
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* | Yes | Yes | Yes | Yes | Yes |
| ADO.NET with .NET Framework 3.5 SP1 with connectivity patch** | 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 | 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.
*Download the new Microsoft OLE DB Driver for SQL Server: https://aka.ms/downloadmsoledbsql.
Important
To connect to an availability group listener, a client must use a TCP connection string.
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Creation and Configuration of Availability Groups (SQL Server)
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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