224.0.2.1 is a Special Purpose IP Address.

The 224.0.0.0/4 Address Block is allocated for multicast address assignments, formely known as the Class D address space.
[ RFC1112, ^ ] , Host Extensions for IP Multicasting

[224.0.2.0 - 224.0.255.255] - AD-HOC Block I
(224.0.0.0/16 minus 224.0.0.0/23)

Addresses in the (224.0.0.0/16 minus 224.0.0.0/23), and the other AD-HOC blocks were traditionally used for assignments for those applications that don't fit in either the Local or Internetwork Control blocks. These addresses MAY be globally routed and are typically used by applications that require small blocks of addressing (e.g., less than a /24 ).
[ RFC5771, ^ ]


224.0.2.1 - "rwho" Group (BSD) (unofficial)
References: [Jon_Postel]

  
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