255.255.255.255/32

This is the limited broadcast address. A host uses it when it needs to send a packet to all hosts on the local network before it knows the network's directed broadcast address.

This address is not publicly routable. Routers do not forward limited broadcasts, because forwarding them would turn local discovery traffic into network-wide noise.

A system administrator will most often see 255.255.255.255 in DHCP (Dynamic Host Configuration Protocol), bootstrapping, discovery traffic, or packet captures from devices that are trying to find a service on the local LAN (local area network).

Firewall tip: 255.255.255.255 is valid only as a local broadcast destination. It is not a valid Internet source address, and it should not be forwarded. Edge firewalls usually drop it when it arrives from the Internet or tries to cross routed boundaries.