FlushIpNetTable function (iphlpapi.h)

Article
10/13/2021

The FlushIpNetTable function deletes all ARP entries for the specified interface from the ARP table on the local computer.

Syntax

IPHLPAPI_DLL_LINKAGE DWORD FlushIpNetTable(
  [in] DWORD dwIfIndex
);

Parameters

[in] dwIfIndex

The index of the interface for which to delete all ARP entries.

Return value

The function returns NO_ERROR (zero) if the function is successful.

If the function fails, the return value is one of the following error codes.

Return code	Description
ERROR_ACCESS_DENIED	Access is denied. This error is returned on Windows Vista and Windows Server 2008 under several conditions that include the following: the user lacks the required administrative privileges on the local computer or the application is not running in an enhanced shell as the built-in Administrator (RunAs administrator).
ERROR_INVALID_PARAMETER	An input parameter is invalid, no action was taken. This error is returned if the dwIfIndex parameter is invalid.
ERROR_NOT_SUPPORTED	The IPv4 transport is not configured on the local computer.
Other	Use FormatMessage to obtain the message string for the returned error.

Remarks

To retrieve the ARP table, call the GetIpNetTable function.

On Windows Vista and later, the FlushIpNetTable function can only be called by a user logged on as a member of the Administrators group. If FlushIpNetTable is called by a user that is not a member of the Administrators group, the function call will fail and ERROR_ACCESS_DENIED is returned. This function can also fail because of user account control (UAC) on Windows Vista and later. If an application that contains this function is executed by a user logged on as a member of the Administrators group other than the built-in Administrator, this call will fail unless the application has been marked in the manifest file with a requestedExecutionLevel set to requireAdministrator. If the application on Windows Vista and later lacks this manifest file, a user logged on as a member of the Administrators group other than the built-in Administrator must then be executing the application in an enhanced shell as the built-in Administrator (RunAs administrator) for this function to succeed.

Note This function executes a privileged operation. For this function to execute successfully, the caller must be logged on as a member of the Administrators group or the NetworkConfigurationOperators group.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	iphlpapi.h
Library	Iphlpapi.lib
DLL	Iphlpapi.dll