TIdStack.IsValidIPv4MulticastGroup Method

Indicates if the specified IP addresss represents a valid IPv4 multicast group address.

Pascal

function IsValidIPv4MulticastGroup(
    const Value: string
): Boolean;

Parameters

Parameters	Description
Value	IP Address to examine.

Returns

Boolean - True when the IP address is a valid multicast group address.

Description

IsValidIPv4MulticastGroup is a Boolean function that indicates if the IP addresss specified in Value represents a valid IPv4 multicast group address.

Multicast group addresses are Class D IP addresses, or those where the four high-order bits in the address are set. In Internet standard "dotted-decimal" notation, multicast group addresses range from 224.0.0.0 to 239.255.255.255. The address 224.0.0.0 is guaranteed not to be assigned to any group, and 224.0.0.1 is assigned to the permanent group of all IP hosts (including gateways). This is used to address all multicast hosts on the directly connected network. There is no multicast address (or any other IP address) for all hosts on the total Internet. The addresses of other well-known, permanent groups are to be published in the "Assigned Numbers" maintained by the IANA (Internet Assigned Numbering Authority).

The Value parameter must contain an IP address in its dotted-decimal representation; if a host name is used in Value, the return value for the method will contain False.

IsValidIPv4MulticastGroup examines the inital byte value from the IP address in Value to ensure that its integer value is in the range represented using the IPv4MCastLo and IPv4MCastHi constants. If the integer value is not in the require range, the return value for the method is False.

Use IsValidIPv6MulticastGroup to determine if an IPv6 address represents a valid multicast group address.