One‑to‑one delivery. A single sender transmits packets to one specific receiver (e.g., your PC fetching a web page).
One‑to‑all delivery. A single sender transmits packets to every device on the local network segment (e.g., ARP requests asking “Who has IP 192.168.1.5?”).
One‑to‑many delivery. A single sender transmits packets only to a specific group of subscribed receivers (e.g., IPTV streams sent only to viewers who’ve joined the channel).
| Feature | Unicast | Broadcast | Multicast |
|---|---|---|---|
| Recipients | 1 host | All hosts on subnet | Hosts in a defined group |
| Use case examples | Web requests, SSH | ARP, DHCP discovery | Video conferencing, stock‑ticker feeds |
| Network impact | Targeted traffic | Highest overhead | Mid‑level efficiency |
| Control | Sender specifies 1 | No control—everyone | Join/leave via group subscription (IGMP) |
Unicast
• Standard for most client‑server apps (HTTP, SSH, email).
• Minimal network “noise.”
Broadcast
• Discovery protocols (ARP, DHCP).
• Should be limited—excessive broadcasts cause storms.
Multicast
• Distribute the same data efficiently to many (live video, stock quotes).
• Requires network support (IGMP, PIM).