IPAddressInformation.IsDnsEligible Property

Definition

Namespace:

System.Net.NetworkInformation

Assembly:

System.Net.NetworkInformation.dll

Gets a Boolean value that indicates whether the Internet Protocol (IP) address is valid to appear in a Domain Name System (DNS) server database.

public:
 abstract property bool IsDnsEligible { bool get(); };

[System.Runtime.Versioning.SupportedOSPlatform("windows")]
public abstract bool IsDnsEligible { get; }

[<System.Runtime.Versioning.SupportedOSPlatform("windows")>]
member this.IsDnsEligible : bool

Public MustOverride ReadOnly Property IsDnsEligible As Boolean

Property Value

Boolean

true if the address can appear in a DNS database; otherwise, false.

Attributes

SupportedOSPlatformAttribute

Examples

The following code example displays the anycast addresses for the network interfaces on the local computer.

void DisplayAnycastAddresses()
{
    int count = 0;
            
    Console::WriteLine( "Anycast Addresses" );
    array<NetworkInterface^>^adapters = NetworkInterface::GetAllNetworkInterfaces();
    System::Collections::IEnumerator^ myEnum13 = adapters->GetEnumerator();
    while ( myEnum13->MoveNext() )
    {
        NetworkInterface ^ adapter = safe_cast<NetworkInterface ^>(myEnum13->Current);
        IPInterfaceProperties ^ adapterProperties = adapter->GetIPProperties();
        IPAddressInformationCollection ^ anyCast = adapterProperties->AnycastAddresses;
        if ( anyCast->Count > 0 )
        {
            Console::WriteLine( adapter->Description );
            System::Collections::IEnumerator^ myEnum14 = anyCast->GetEnumerator();
            while ( myEnum14->MoveNext() )
            {
                IPAddressInformation ^ any = safe_cast<IPAddressInformation ^>(myEnum14->Current);
                Console::WriteLine( "  Anycast Address .......................... : {0} {1} {2}", 
                    any->Address, any->IsTransient ? "Transient" : "", 
                    any->IsDnsEligible ? "DNS Eligible" : "" );
                count++;
            } 
            Console::WriteLine();
        }
    }
    if (count == 0)
    {
        Console::WriteLine("  No anycast addresses were found.");
        Console::WriteLine();
    }
}

public static void DisplayAnycastAddresses()
{
    int count = 0;

    Console.WriteLine("Anycast Addresses");
    NetworkInterface[] adapters  = NetworkInterface.GetAllNetworkInterfaces();
    foreach (NetworkInterface adapter in adapters)
    {
        IPInterfaceProperties adapterProperties = adapter.GetIPProperties();
        IPAddressInformationCollection anyCast = adapterProperties.AnycastAddresses;
        if (anyCast.Count >0)
        {

            Console.WriteLine(adapter.Description);
            foreach (IPAddressInformation any in anyCast)
            {
                Console.WriteLine("  Anycast Address .......................... : {0} {1} {2}",
                    any.Address,
                    any.IsTransient ? "Transient" : "",
                    any.IsDnsEligible ? "DNS Eligible" : ""
                );
                count++;
            }
            Console.WriteLine();
        }
    }
    if (count == 0)
    {
        Console.WriteLine("  No anycast addressses were found.");
        Console.WriteLine();
    }
}

Public Shared Sub DisplayAnycastAddresses() 
    Dim count as Integer = 0
    
    Console.WriteLine("Anycast Addresses")
    Dim adapters As NetworkInterface() = NetworkInterface.GetAllNetworkInterfaces()
    Dim adapter As NetworkInterface
    For Each adapter In  adapters
        Dim adapterProperties As IPInterfaceProperties = adapter.GetIPProperties()
        Dim anyCast As IPAddressInformationCollection = adapterProperties.AnycastAddresses
        If anyCast.Count > 0 Then
            Console.WriteLine(adapter.Description)
            Dim any As IPAddressInformation
            For Each any In  anyCast
                Console.WriteLine("  Anycast Address .......................... : {0} {1} {2}", any.Address, IIf(any.IsTransient, "Transient", ""), IIf(any.IsDnsEligible, "DNS Eligible", ""))
            'TODO: For performance reasons this should be changed to nested IF statements
            'TODO: For performance reasons this should be changed to nested IF statements
                count += 1
            Next any
            Console.WriteLine()
        End If
    Next adapter

    if count = 0 then
        Console.WriteLine("  No anycast addresses were found.")
        Console.WriteLine()
    End if
End Sub

Remarks

Addresses in the range 169.254.0.0 to 169.254.255.255 are not DNS eligible. These addresses are reserved for Automatic Private IP Addressing (APIPA).