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Multicast Addresses

You landed here because the address you looked up is a multicast group address, not a unicast host. RFC 5771 reserves 224.0.0.0/4 for IPv4 multicast and RFC 4291 reserves ff00::/8 for IPv6 multicast. These ranges address groups of receivers rather than individual hosts, so asking “who owns this IP” is a category error — it is a delivery mechanism, not an endpoint.

IPv4 multicast
224.0.0.0/4
RFC 5771
IPv6 multicast
ff00::/8
RFC 4291

Frequently asked questions

What protocol uses 224.0.0.1?

224.0.0.1 is the 'all hosts on this subnet' multicast group. Every IPv4 host listens to it. Protocols that need to talk to all hosts on a link — IGMP queries, ICMP router discovery, mDNS on some stacks — send to 224.0.0.1. It is permanently reserved as a link-scoped multicast group and is never routed off the local segment.

Why can I not ping a multicast address from the internet?

Internet-wide multicast routing (MBONE, SSM) was never widely deployed outside of research networks and a handful of enterprise content-delivery use cases. Most public transit providers do not carry multicast, so ICMP echo to a group address never finds a receiver. Inside a controlled network with IGMP snooping and PIM configured you can multicast freely, but you cannot do it across arbitrary internet paths.

What is the difference between SSM and ASM multicast?

ASM (Any-Source Multicast) is the original model: a receiver joins a group address and receives traffic from any sender. It requires shared trees and rendezvous points, and is a pain to troubleshoot. SSM (Source-Specific Multicast, RFC 4607, 232.0.0.0/8 for IPv4) requires the receiver to specify (source, group) pairs — it is simpler, avoids RP scaling problems, and is what most modern multicast deployments (financial market data, IPTV) actually use.

What is 239.0.0.0/8 used for?

239.0.0.0/8 is the administratively-scoped multicast range, RFC 2365. It is the multicast equivalent of RFC 1918 — use it freely inside your organisation, but do not expect it to cross administrative boundaries. Enterprise video distribution and IP surveillance systems commonly use 239.x addresses.

Are IPv6 multicast addresses (ff00::/8) the same idea?

Yes, with better scoping. IPv6 bakes the scope directly into the address: ff02::1 is link-local all-nodes, ff05::1 is site-local, ff0e::1 is global. That removes the need for TTL hacks that IPv4 multicast relies on, and makes it obvious at a glance how far a packet is allowed to travel. All IPv6 hosts must join ff02::1 on every interface.

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