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Good morning all ,

I have an alwayson instance with a multisubnet listener

I configured RegisterAllProvidersIP = 0 in order to register a single DNS entry

HostRecordTTL is configured at 1200 seconds

I would like if with this configuration I will have timoeout during the failover

if so how much time is needed for the application to connect to the lsitener

thanks

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  • You want the failover to timeout and fail after 20 minutes? Nov 28, 2020 at 13:48

2 Answers 2

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if so how much time is needed for the application to connect to the lsitener

Since you said HostRecordTTL is set to 1200 seconds, the application will take up to 20 minutes to reconnect after a failover that crosses subnets.

Ideally you should set RegisterAllProvidersIP = 1, and update your application's connection string to include MultiSubnetFailover = True. This will provide the best failover experience.

If your application uses a driver that doesn't support this setting, or you can't change the connection string for some other reason, and you need to reduce the failover timeout, then you'll need to lower the HostRecordTTL setting.

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I recently published a new blog showing how you can reduce failover times for SQL Server on Amazon EC2 instance using Network Load Balancer.

When a legacy application that doesn't support MultiSubnetFailover = True you have to set RegisterAllProvidersIP = 0 but the failover from a primary to a secondary node can take a long time depending on the TTL (as much as 15 minutes) because it requires a DNS replication. With this solution, you can reduce failover times to around a minute.

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  • There's no indication the OP's on AWS. Does this apply on-prem too? You can edit the answer to add detail. Nov 14, 2022 at 19:47

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