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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: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8
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