What does Windows error code 9976 (DNS_ERROR_CLIENT_SUBNET_DOES_NOT_EXIST) mean?

DNS_ERROR_CLIENT_SUBNET_DOES_NOT_EXIST

DNS_ERROR_CLIENT_SUBNET_DOES_NOT_EXIST means a policy references a named client subnet that is absent from the target DNS server.

What to check for DNS_ERROR_CLIENT_SUBNET_DOES_NOT_EXIST

• List client subnets on the specific DNS server that serves the policy.
• Verify the spelling and whether the policy was deployed consistently to every DNS server that should evaluate it.
• Check that the subnet definition contains the intended IPv4 and/or IPv6 prefixes before adding it.

Get-DnsServerClientSubnet
Get-DnsServerQueryResolutionPolicy -ZoneName "example.com"

Microsoft: Get-DnsServerClientSubnet

Microsoft: Add-DnsServerClientSubnet

Microsoft: Add-DnsServerQueryResolutionPolicy

Where the result is returned

This result is Win32 system error 9976 (0x000026F8) from winerror.h. AllStat describes it as “The client subnet does not exist on the DNS server.”