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IPAddress.ScopeId Property

Gets or sets the IPv6 address scope identifier.

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

public long ScopeId { get; set; }

Property Value

Type: System.Int64
A long integer that specifies the scope of the address.


AddressFamily = InterNetwork.


scopeId < 0

- or -

  • scopeId > 0x00000000FFFFFFFF

The meaning of ScopeId changes depending on the context in which it is used.

  • Link-local address. On a host with multiple interfaces connected to separate links, the same link-local address can be assigned to multiple interfaces. To eliminate this ambiguity, a scope identifier is used to specify the interface over which messages are exchanged.


Link-local addresses, identified by the Format Prefix (FP) FE80, are used by nodes when communicating with neighboring nodes on the same link.

  • Site-local addresses. A host can be connected to multiple sites. In this case, a scope identifier is used to indicate a specific site to communicate with.


Site-local addresses, identified by the Format Prefix (FP) FEC0, are used by nodes when communicating on private intranets.

The notation that is used to specify the ScopeId with an address is Address%ScopeId. For example, FE80::5EFE:

          // Display the type of address family supported by the server. If the
          // server is IPv6-enabled this value is: InternNetworkV6. If the server
          // is also IPv4-enabled there will be an additional value of InterNetwork.
          Console.WriteLine("AddressFamily: " + curAdd.AddressFamily.ToString());

          // Display the ScopeId property in case of IPV6 addresses.
          if(curAdd.AddressFamily.ToString() == ProtocolFamily.InterNetworkV6.ToString())
            Console.WriteLine("Scope Id: " + curAdd.ScopeId.ToString());

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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