What does Windows error code 9976 (DNS_ERROR_CLIENT_SUBNET_DOES_NOT_EXIST) mean?

 
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DNS_ERROR_CLIENT_SUBNET_IS_ACCESSED DNS_ERROR_CLIENT_SUBNET_ALREADY_EXISTS

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.”. The code is useful only together with the API that failed, because multiple Windows components can reuse system-error values while imposing different retry and cleanup rules.

Diagnostic sequence

  • Call GetLastError immediately after the failing API and save this result, the function name, all relevant flags, and the target path, handle, service, device, account, or policy object.
  • Capture the component log that owns the dns / client / subnet / does / exist operation and retain the original numeric value before a framework converts it to an HRESULT or exception.
  • compare preconditions with the API documentation and reproduce with a minimal request before changing system-wide configuration.

Retry this result only after the resource or state named in “The client subnet does not exist on the DNS server.” has changed. For invalid parameters, unsupported formats, missing objects, policy restrictions, and access failures, correct the input or configuration instead of immediately repeating the same call.

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