DNS_ERROR_SUBNET_ALREADY_EXISTS 0x800726FB

Error code 9979 · HRESULT 0x800726FB

WINDOWS

The IP subnet that is being added, already exists in the client subnet.

Windows troubleshooting diagram: Device Manager warning and a system file scan
Windows errors: check drivers, system files and Event Viewer, in that order.

What it means

DNS_ERROR_SUBNET_ALREADY_EXISTS is a Windows error code (system error 9979, returned as HRESULT 0x800726FB) reported by Windows. Its official message is: “The IP subnet that is being added, already exists in the client subnet.”

How to fix DNS_ERROR_SUBNET_ALREADY_EXISTS

  1. Test connectivity to the remote host first (ping, then the exact port)
  2. Check firewall, VPN and proxy rules for the involved process
  3. Run 'ipconfig /flushdns' and 'netsh interface ip reset', then reboot

Related errors

DNS_ERROR_SUBNET_DOES_NOT_EXISTDNS_ERROR_POLICY_LOCKEDDNS_ERROR_CLIENT_SUBNET_ALREADY_EXISTSDNS_ERROR_POLICY_INVALID_WEIGHTDNS_ERROR_CLIENT_SUBNET_DOES_NOT_EXISTDNS_ERROR_POLICY_INVALID_NAMEDNS_ERROR_CLIENT_SUBNET_IS_ACCESSED

Source: Microsoft WinError.h

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