C# Signature:

[DllImport("iphlpapi.dll", SetLastError=true)]
static extern int GetBestInterface(UInt32 DestAddr, out UInt32 BestIfIndex);

VB Signature:

Declare Function GetBestInterface Lib "iphlpapi.dll" (TODO) As TODO

User-Defined Types:

None.

Notes:

DestAddr is a 32 bit representation of the four IP bytes. For .NET 1.0, you can get this from IPAddress.Address. In .NET 1.1, this is obsolete. You can use BitConverter.ToUInt32(IPAddress.GetAddressBytes()) instead.

Tips & Tricks:

Use GetAdaptersInfo to determine which adapter the index corresponds to.

Sample Code:

Please add some!

Alternative Managed API:

Do you know one? Please contribute it!