IPv4 Multicast Address Space Registry

Host Extensions for IP Multicasting [RFC1112] specifies the extensions
required of a host implementation of the Internet Protocol (IP) to
support multicasting.  The multicast addresses are in the range
224.0.0.0 through 239.255.255.255. Address assignments are listed below.

The range of addresses between 224.0.0.0 and 224.0.0.255, inclusive,
is reserved for the use of routing protocols and other low-level
topology discovery or maintenance protocols, such as gateway discovery
and group membership reporting.  Multicast routers should not forward
any multicast datagram with destination addresses in this range,
regardless of its TTL.