DuplicateAddressDetectionState Enumeration
Collapse the table of content
Expand the table of content

DuplicateAddressDetectionState Enumeration

 

Specifies the current state of an IP address.

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

Public Enumeration DuplicateAddressDetectionState

Member nameDescription
Deprecated

The address is valid, but it is nearing its lease lifetime and should not be used by applications.

Duplicate

The address is not unique. This address should not be assigned to the network interface.

Invalid

The address is not valid. A nonvalid address is expired and no longer assigned to an interface; applications should not send data packets to it.

Preferred

The address is valid and its use is unrestricted.

Tentative

The duplicate address detection procedure's evaluation of the address has not completed successfully. Applications should not use the address because it is not yet valid and packets sent to it are discarded.

To help ensure that all interfaces on a network have a unique address, the interface host is responsible for running a "duplicate address detection" algorithm on unicast addresses. The purpose of this algorithm is to attempt to prevent non-unique addresses on the network. This process is defined in IETF RFC 1971.

This enumeration is used by the UnicastIPAddressInformation and MulticastIPAddressInformation classes. Instances of this class are returned when you retrieve the unicast address information for a NetworkInterface object.

The following code example determines unicast address information.

Public Shared Sub DisplayUnicastAddresses() 

    Console.WriteLine("Unicast Addresses")
    Dim adapters As NetworkInterface() = NetworkInterface.GetAllNetworkInterfaces()
    Dim adapter As NetworkInterface
    For Each adapter In  adapters
        Dim adapterProperties As IPInterfaceProperties = adapter.GetIPProperties()
        Dim uniCast As UnicastIPAddressInformationCollection = adapterProperties.UnicastAddresses
        If uniCast.Count > 0 Then
            Console.WriteLine(adapter.Description)
            Dim lifeTimeFormat As String = "dddd, MMMM dd, yyyy  hh:mm:ss tt"
            Dim uni As UnicastIPAddressInformation
            For Each uni In  uniCast
                Dim [when] As DateTime

                Console.WriteLine("  Unicast Address ......................... : {0}", uni.Address)
                Console.WriteLine("     Prefix Origin ........................ : {0}", uni.PrefixOrigin)
                Console.WriteLine("     Suffix Origin ........................ : {0}", uni.SuffixOrigin)
                Console.WriteLine("     Duplicate Address Detection .......... : {0}", uni.DuplicateAddressDetectionState)

                ' Format the lifetimes as Sunday, February 16, 2003 11:33:44 PM
                ' if en-us is the current culture.
                ' Calculate the date and time at the end of the lifetimes.    
                [when] = DateTime.UtcNow + TimeSpan.FromSeconds(uni.AddressValidLifetime)
                [when] = [when].ToLocalTime()
                Console.WriteLine("     Valid Life Time ...................... : {0}", [when].ToString(lifeTimeFormat, System.Globalization.CultureInfo.CurrentCulture))
                [when] = DateTime.UtcNow + TimeSpan.FromSeconds(uni.AddressPreferredLifetime)
                [when] = [when].ToLocalTime()
                Console.WriteLine("     Preferred life time .................. : {0}", [when].ToString(lifeTimeFormat, System.Globalization.CultureInfo.CurrentCulture))

                [when] = DateTime.UtcNow + TimeSpan.FromSeconds(uni.DhcpLeaseLifetime)
                [when] = [when].ToLocalTime()
                Console.WriteLine("     DHCP Leased Life Time ................ : {0}", [when].ToString(lifeTimeFormat, System.Globalization.CultureInfo.CurrentCulture))
            Next uni
            Console.WriteLine()
        End If
    Next adapter

End Sub 'DisplayUnicastAddresses

.NET Framework
Available since 2.0
Return to top
Show:
© 2016 Microsoft