What Is Unicast?
Unicast — one-to-one delivery — a packet addressed to exactly one destination, the way the vast majority of network traffic travels.
How it works
Web browsing, email, SSH, file transfers — all unicast: your device to one server and back. Switches deliver unicast frames out a single learned port; routers forward toward one destination network. Its counterparts are broadcast (everyone) and multicast (a subscribed group).
Why it matters
The delivery-mode trio anchors many exam questions, and knowing that unknown-unicast frames get flooded by switches (until the MAC is learned) explains real behaviours you'll see in labs and packet captures.
Frequently asked questions
What is unicast in simple terms?
Point-to-point delivery: one sender, one receiver — like a letter to a single address.
What happens if a switch doesn't know the unicast destination?
It floods the frame out all ports in the VLAN (unknown unicast flooding) until it learns where that MAC lives.
Is anycast the same as unicast?
Anycast uses one address on many servers, delivering to the nearest — the packet still reaches one receiver, but which one depends on routing.
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