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DnsPermissionAttribute Class

Specifies permission to request information from Domain Name Servers.

Namespace:  System.Net
Assembly:  System (in System.dll)

<SerializableAttribute> _
<AttributeUsageAttribute(AttributeTargets.Assembly Or AttributeTargets.Class Or AttributeTargets.Struct Or AttributeTargets.Constructor Or AttributeTargets.Method, AllowMultiple := True,  _
	Inherited := False)> _
Public NotInheritable Class DnsPermissionAttribute _
	Inherits CodeAccessSecurityAttribute
Dim instance As DnsPermissionAttribute

The security information declared by DnsPermissionAttribute is stored in the metadata of the attribute target, which is the class to which the DnsPermissionAttribute is applied. The system then accesses this information at run time. The SecurityAction that is passed to the constructor determines the allowable DNS targets.

These security attributes are used only for Declarative Security. For Imperative Security, use the corresponding DnsPermission class.

Security access is either fully restricted or fully unrestricted. Set the Unrestricted property to true to grant access, or false for no access. Set this property as a named parameter.

For more information about using attributes, see Extending Metadata Using Attributes.

The following example uses DnsPermissionAttribute to apply declarative security to a custom class.

' Uses the DnsPermissionAttribute to restrict access only to those who have permission.
<DnsPermission(SecurityAction.Demand, Unrestricted := true)>  _
Public Class MyClass1

   Public Shared Function GetIPAddress() As IPAddress
      Dim ipAddress As IPAddress = Dns.Resolve("localhost").AddressList(0)
      Return ipAddress
   End Function 'GetIPAddress

   Public Shared Sub Main()
         ' Grants Access.
         Console.WriteLine(("Access granted" + ControlChars.NewLine + " The local host IP Address is :" + MyClass1.GetIPAddress().ToString()))
      ' Denies Access. 
      Catch securityException As SecurityException
         Console.WriteLine("Access denied")
      End Try 
   End Sub 'Main 
End Class '[MyClass1]
//Uses the DnsPermissionAttribute to restrict access only to those who have permission.
[DnsPermission(SecurityAction::Demand, Unrestricted = true)]
public __gc class MyClass{
    static IPAddress* GetIPAddress(){
        IPAddress* ipAddress = Dns::Resolve(S"localhost")->AddressList[0];
        return ipAddress;

int main(){
        //Grants Access.
        Console::WriteLine(S" Access granted\n The local host IP Address is :{0}", MyClass::GetIPAddress());
    // Denies Access.
    catch(SecurityException* securityException){
        Console::WriteLine(S"Access denied");	

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0