Cluster HostRecordTTL

Question

PS C:\Windows\system32> get-clusterresource "ClusterResourceName" | Get-ClusterParameter

Object Name Value Type

---

ClusterResourceName Name ClusterResourceName String
ClusterResourceName DnsName ClusterResourceName String
ClusterResourceName Aliases String
ClusterResourceName RemapPipeNames 0 UInt32
ClusterResourceName HostRecordTTL 60 UInt32

1. We see there is a TTL record for the cluster resource names, which we can configure. What is the minimum value we can set? Can we set 0?
2. We see that aside from the TTL DNS records itself, we also need time for DNS to replicate the changes. That adds another few minutes to the failover. Do you know of any way to expedite this update on both levels (Cluster & DNS)?

Answer 1

Hi,

If you want to speed up the DNS record sync up speed, it's not related to the TTL value, the time depends on the AD replication time, and as far as I know, by default, the AD replication time is around 2-3 minutes, and seems we are unable to speed up the time.

Thanks for your time!
Best Regards,
Anne

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Answer 2

Hi,

The ClusterResourceName Host RecordTTL is the DNS cache live time.

By default, clients cache cluster DNS records for 20 minutes. By reducing HostRecordTTL, the Time to Live (TTL), for the cached record, legacy clients may reconnect more quickly. However, reducing the HostRecordTTL setting may also result in increased traffic to the DNS servers.

If you would like to reduce the TTL, we may use the command below. We can set it to 0, while it's not recommended to do so.

https://learn.microsoft.com/en-us/previous-versions/windows/desktop/mscs/distributed-net-names-hostrecordttl

https://learn.microsoft.com/en-us/powershell/module/failoverclusters/set-clusterparameter?view=windowsserver2019-ps

Thanks for your time!
Best Regards,
Anne

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Answer 3

I tried the TTL value of 0, but that didn't help, since we still saw about 2-3 minutes worth of time until the DNS server on the alternate site received a replication of the new IP for the name. Any recommendations on how to speed up the intersite DNS replication?