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Unicast

Sending a message to one computer; on a one-to-one basis

Wikipedia contributorsAdapted for Fathomly · View authors
1 min read
Source updated November 11, 2025
Image credit is listed at the end of this article.
Routing schemes
Unicast
Broadcast
Multicast
Anycast

In computer networking, unicast is a one-to-one transmission from one point in the network to another point; that is, one sender and one receiver, each identified by a network address.

Unicast is in contrast to multicast and broadcast which are one-to-many transmissions.

Internet Protocol unicast delivery methods such as Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are typically used.

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Sources and credits

This article is adapted from the Wikipedia article “Unicast”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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Related topics

Anycast

Anycast is a network addressing and routing methodology in which a single IP address is shared by devices in multiple locations. Routers direct packets addressed to this destination to the location nearest the sender, using their normal decision-making algorithms, typically the lowest number of BGP network hops.

Broadcast, unknown-unicast and multicast traffic

Broadcast, unknown-unicast and multicast traffic is network traffic transmitted using one of three methods of sending data link layer network traffic to a destination of which the sender does not know the network address. This is achieved by sending the network traffic to multiple destinations on an Ethernet network.

IP address

An Internet Protocol address is a numerical label, such as 192.168.1.1 or 2001:0db8:0000:0000:0000:8a2e:0370:7334, that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface identification, and location addressing.