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Configuring Multicast Scopes

Updated: March 28, 2003

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Windows Server 2003 DHCP service offers MADCAP support in the form of multicast scopes. MADCAP supports dynamic assignment and configuration of IP multicast addresses on TCP/IP-based networks. Multicast scopes provide ranges of Class D IP addresses, which are reserved for multicast operation, by using directed transmission from one point to multiple points. With the exception of DHCP-assignable options, which multicast scopes do not support, you can configure a multicast scope in the same way that you configure a regular DHCP scope.

Multicast IP addresses allow multiple clients to receive data that a server sends to a single IP address, enabling point-to-multipoint communication. This type of transmission is often used for streaming media transmissions, such as video conferencing.


  • In all TCP/IP networks, each computer requires a unique primary computer IP address from one of the standard address classes used for building the network (Class A, B, or C range). You must assign this required primary computer IP address before you can configure a computer to support and use secondary IP addresses such as multicast IP addresses.

Although the Windows Server 2003 DHCP service supports both DHCP and MADCAP, the services function independently; clients that do not obtain IP addresses from the DHCP service can still obtain MADCAP addresses from the DHCP service. DHCP scopes are used to allocate IP address ranges from Class A, B, or C addressing schemes, which enable unicast for point-to-point communication between networked computers. MADCAP scopes allocate Class D IP addresses to enable point-to-multipoint communication.

To configure a MADCAP scope

  1. In the DHCP snap-in, select and right-click the DHCP server you want to configure. The New Multicast Scope Wizard appears.

  2. In the New Multicast Scope Wizard, type a name and description for this multicast scope.

  3. Set the multicast IP address range and Time to Live (TTL).

  4. Add any exclusion ranges and the lease duration, then activate the multicast scope.


  • Clients that use MADCAP must be configured to use the MADCAP API. For more information about writing or programming applications that use the MADCAP API, see the MSDN Online link on the Web Resources page at

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