224.0.0.0/4 — multicast, where addresses are groups
224.0.0.0/4 — 268,435,456 addresses from 224.0.0.0 to 239.255.255.255 — is IPv4 multicast, now governed by RFC 5771. It is the old "Class D", and it breaks the first rule you learned about IP addresses: a multicast address does not identify a machine. It names a group, and any number of machines can join it.
Send one packet to 224.0.0.251 and every mDNS listener on the link gets a copy. That is the whole model: one-to-many delivery, with the network duplicating packets only where the distribution tree branches.
| Range start | 224.0.0.0 |
| Range end | 239.255.255.255 |
| Subnet mask | 240.0.0.0 |
| Wildcard mask | 15.255.255.255 |
| Total addresses | 268,435,456 |
Multicast addresses name groups, not subnets — there is no network, broadcast or usable-host concept here; the table shows the class's boundaries.
Groups, not hosts
You never assign a multicast address to an interface the way you assign 192.168.1.10. Instead, applications subscribe: hosts signal membership with IGMP — the protocol by which a host tells its router "please forward group X to me" — and routers build a per-group distribution tree. The bottom slice, 224.0.0.0/24, is reserved for local-link protocol traffic that routers must not forward.
The famous names live there: 224.0.0.1 is all-hosts on the local segment, 224.0.0.2 is all-routers, 224.0.0.251 is mDNS (what makes .local names and AirPrint work), 224.0.0.252 is LLMNR, and 224.0.0.5 plus 224.0.0.6 belong to OSPF.
Why you can't scan it
A ping sweep of 224/4 is meaningless: there is no host "at" an address to answer. Pinging 224.0.0.1 does work as a party trick — every host on the link replies — but that is the all-hosts group, not an enumeration. Discovery on multicast networks is service-driven: you announce or query groups like mDNS rather than sweeping ranges.
Multicast also mostly does not cross the public Internet, the mbone experiment aside — so treat 224/4 as link- and enterprise-local plumbing and block it at borders.
CIDR Calculator
Run the math on 224.0.0.0/4 — or any other block
Frequently asked questions
What is 224.0.0.1?
The all-hosts multicast group: every multicast-capable host on the local link is a member. Pinging it is a quick way to see which devices on your segment respond.
Is 224.0.0.0/4 a subnet I can assign?
No. It is the multicast class — addresses name groups that hosts join, not interfaces. Routing is per-group, built by IGMP and multicast routing protocols.
What is 224.0.0.251 used for?
mDNS, multicast DNS (RFC 6762). Devices resolve .local names and discover services like printers by querying this group on UDP port 5353.
How many addresses are in 224.0.0.0/4?
268,435,456 (2^28) — a sixteenth of the IPv4 space, from 224.0.0.0 through 239.255.255.255.