A network host is a
computer or other device connected to a
computer network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are ...
. A host may work as a
server offering information resources, services, and applications to users or other hosts on the network. Hosts are assigned at least one
network address
A network address is an identifier for a node or host on a telecommunications network. Network addresses are designed to be unique identifiers across the network, although some networks allow for local, private addresses, or locally administer ...
.
A computer participating in networks that use the
Internet protocol suite
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the sui ...
may also be called an IP host. Specifically, computers participating in the
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
are called Internet hosts. Internet hosts and other IP hosts have one or more
IP address
An Internet Protocol address (IP address) is a numerical label such as that is connected to a computer network that uses the Internet Protocol for communication.. Updated by . An IP address serves two main functions: network interface ident ...
es assigned to their network interfaces. The addresses are configured either manually by an administrator, automatically at startup by means of the
Dynamic Host Configuration Protocol (DHCP), or by
stateless address autoconfiguration
In computer networking, a link-local address is a unicast network address that is valid only for communications within the subnetwork that the host is connected to. Link-local addresses are most often assigned automatically with a process known as ...
methods.
Network hosts that participate in applications that use the
client–server model
The client–server model is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients. Often clients and servers communicate ove ...
of computing, are classified as
server or
client
Client(s) or The Client may refer to:
* Client (business)
* Client (computing), hardware or software that accesses a remote service on another computer
* Customer or client, a recipient of goods or services in return for monetary or other valuabl ...
systems. Network hosts may also function as nodes in
peer-to-peer
Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network. They are said to form a peer-to-peer ...
applications, in which all nodes share and consume resources in an equipotent manner.
Origins
In
operating systems, the term ''terminal host'' denotes a
time-sharing
In computing, time-sharing is the sharing of a computing resource among many users at the same time by means of multiprogramming and multi-tasking.DEC Timesharing (1965), by Peter Clark, The DEC Professional, Volume 1, Number 1
Its emergence ...
computer or
multi-user software
Multi-user software is computer software that allows access by multiple users of a computer. Time-sharing systems are multi-user systems. Most batch processing systems for mainframe computers may also be considered "multi-user", to avoid leaving t ...
providing services to
computer terminal
A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. The teletype was an example of an early-day hard-copy terminal and ...
s, or a computer that provides services to smaller or less capable devices, such as a
mainframe computer serving
teletype
A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Init ...
terminals or video terminals. Other examples of this architecture include a
telnet
Telnet is an application protocol used on the Internet or local area network to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet contr ...
host connected to a telnet server and an
xhost In the X Window System, programs run as X clients, and as such they connect to the X display server, possibly via a computer network. Since the network may be accessible to other users, a method for forbidding access to programs run by users differe ...
connected to an
X Window client.
The term ''Internet host'' or just ''host'' is used in a number of
Request for Comments
A Request for Comments (RFC) is a publication in a series from the principal technical development and standards-setting bodies for the Internet, most prominently the Internet Engineering Task Force (IETF). An RFC is authored by individuals or g ...
(RFC) documents that define the Internet and its predecessor, the
ARPANET
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control and one of the first networks to implement the TCP/IP protocol suite. Both technologies became the technical fou ...
. RFC 871 defines a host as a general-purpose computer system connected to a communications network for "... the purpose of achieving resource sharing amongst the participating operating systems..."
While the ARPANET was being developed, computers connected to the network were typically mainframe computer systems that could be accessed from
dumb terminal
A computer terminal is an electronic or electromechanical hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. The teletype was an example of an early-day hard-copy terminal a ...
s connected via
serial port
In computing, a serial port is a serial communication interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits simultaneously in parallel. ...
s. Since these terminals did not host software or perform computations themselves, they were not considered ''hosts'' as they were not connected to any
IP network
The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...
, and were not assigned IP addresses. User computers connected to the ARPANET at a
packet-switching node A packet-switching node is a node in a packet-switching network that contains data
In the pursuit of knowledge, data (; ) is a collection of discrete Value_(semiotics), values that convey information, describing quantity, qualitative property, ...
were considered hosts.
Nodes, hosts, and servers
A
network node
In telecommunications networks, a node (, ‘knot’) is either a redistribution point or a communication endpoint. The definition of a node depends on the network and protocol layer referred to. A physical network node is an electronic device ...
is any device participating in a network. A host is a node that participates in user applications, either as a server, client, or both. A
server is a type of host that offers resources to the other hosts. Typically a server accepts connections from
clients who request a service function.
Every network host is a node, but not every network node is a host.
Network infrastructure hardware, such as
modem
A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by Modulation#Digital modulati ...
s,
Ethernet hub
An Ethernet hub, active hub, network hub, repeater hub, multiport repeater, or simply hub is a network hardware device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/out ...
s, and
network switch
A network switch (also called switching hub, bridging hub, and, by the IEEE, MAC bridge) is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destination device.
A netw ...
es are not directly or actively participating in application-level functions, and do not necessarily have a network address, and are not considered to be network hosts.
See also
*
Communication endpoint
A communication endpoint is a type of communication network node. It is an interface exposed by a communicating party or by a communication channel. An example of the latter type of a communication endpoint is a publish-subscribe topic or a grou ...
*
End system
*
Port (computer networking)
In computer networking, a port is a number assigned to uniquely identify a connection endpoint and to direct data to a specific service. At the software level, within an operating system, a port is a logical construct that identifies a specific ...
*
Terminal (telecommunication)
In the context of telecommunications, a terminal is a device which ends a telecommunications link and is the point at which a signal enters or leaves a network. Examples of terminal equipment include telephones, fax machines, computer termina ...
References
External links
*{{cite IETF , rfc=1122 , title=Requirements for Internet Hosts -- Communication Layers , editor=R. Braden , date=October 1989
Networking hardware