0x0000251D DNS_ERROR_RCODE_FORMAT_ERROR — Windows Error Code

Q: What does the Windows error code 0x0000251D mean?

It is the Win32 / NTSTATUS code DNS_ERROR_RCODE_FORMAT_ERROR (decimal 9501). DNS server unable to interpret format.

Q: How do I decode 0x0000251D in PowerShell?

Run [ComponentModel.Win32Exception]::new(9501).Message in any PowerShell session. For HRESULT-style codes, use err.exe from the Windows SDK or the WinDbg !error command.

Q: Where does Windows typically log this error?

It depends on the originating subsystem (Windows Update → %WinDir%\WindowsUpdate.log; AD/Kerberos → Security event log on the DC; BSOD → minidump under C:\Windows\Minidump; MSI → %TEMP%\msi*.log; WMI → Microsoft-Windows-WMI-Activity). Always cross-reference the timestamp and module name with the Application and System event logs.

Description

DNS_ERROR_RCODE_FORMAT_ERROR (hex code 0x0000251D, decimal 9501) is a Windows error-level error code in the DNS Errors family. Microsoft surfaces this code through the Win32 API, the Common Language Runtime, the kernel, the event log, PowerShell, command-line tools (sfc, dism, gpupdate, sc), and Windows-side applications such as Outlook, Teams, Office, and System Center.

DNS server unable to interpret format.

This page documents what triggers 0x0000251D, the most common scenarios where it appears, the likely root causes, and a step-by-step troubleshooting workflow you can run against affected endpoints. It is intended for system administrators, MSP technicians, helpdesk engineers, and anyone diagnosing Windows behavior in a managed environment.

In-depth explanation

This is an error-severity code. Windows uses it to signal a failed operation that prevented the caller from completing its work. The underlying cause can range from a permissions or quota issue to a corrupted system component, missing dependency, or unreachable service.

It is part of the DNS / WinSock error space. It surfaces in DNS Manager, nslookup, Resolve-DnsName, and any application performing name resolution.

The code can be looked up programmatically in PowerShell with [ComponentModel.Win32Exception]::new(9501).Message (for Win32 / NTSTATUS codes that map cleanly), or with net helpmsg 9501 for the legacy decimal range. For HRESULT-style codes, decode the facility and code with err.exe from the SDK or via the WinDbg !error command.

Common causes

Target hostname does not exist or zone not authoritative.
Recursive resolver (Active Directory DNS, public 1.1.1.1, etc.) returning SERVFAIL.
Stale negative cache on the client — flush with ipconfig /flushdns.
Conditional forwarder or split-horizon misconfiguration.
DNSSEC validation failing on the recursive resolver.

Troubleshooting steps

Verify resolution from the client: Resolve-DnsName <hostname> -Server <dns-server>.
Flush the local cache: ipconfig /flushdns; clear the negative cache.
Inspect the DNS server event log for SERVFAIL, REFUSED, or recursion errors.
If conditional forwarding is in play, validate the forwarder is reachable and the zone is delegated.
Test against a known-good public resolver (1.1.1.1, 8.8.8.8) to isolate whether the issue is local or upstream.

Decode in PowerShell

# Decode 0x0000251D (9501) in PowerShell
[ComponentModel.Win32Exception]::new(9501).Message

# Or via WinDbg / err.exe (Windows SDK)
# err 0x0000251D

# Or net helpmsg (legacy decimal range only)
# net helpmsg 9501

Frequently asked questions

What does the Windows error code 0x0000251D mean?

It is the Win32 / NTSTATUS code DNS_ERROR_RCODE_FORMAT_ERROR (decimal 9501). DNS server unable to interpret format.

How do I decode 0x0000251D in PowerShell?

Run [ComponentModel.Win32Exception]::new(9501).Message in any PowerShell session. For HRESULT-style codes, use err.exe from the Windows SDK or the WinDbg !error command.

Where does Windows typically log this error?

It depends on the originating subsystem (Windows Update → %WinDir%\WindowsUpdate.log; AD/Kerberos → Security event log on the DC; BSOD → minidump under C:\Windows\Minidump; MSI → %TEMP%\msi*.log; WMI → Microsoft-Windows-WMI-Activity). Always cross-reference the timestamp and module name with the Application and System event logs.

Is this code recoverable?

Critical-severity codes usually require kernel-level investigation (driver, hardware, system file repair). Error and warning codes are typically recoverable through the troubleshooting workflow on this page — start with the elevated-shell + log review steps.

Should I open a Microsoft support case for this?

Open a case if the error reproduces after applying the troubleshooting steps, particularly if it blocks production workloads, occurs across multiple endpoints, or is associated with a security boundary (BitLocker recovery, Kerberos failure, DCOM hardening, SmartScreen / WDAC). Have a fresh CBS log, minidump, or Get-WinEvent export ready before opening the case.