A network domain is an administrative grouping of multiple private
computer networks or local hosts within the same
infrastructure. Domains can be identified using a
domain name
A domain name is a string that identifies a realm of administrative autonomy, authority or control within the Internet. Domain names are often used to identify services provided through the Internet, such as websites, email services and more. As ...
; domains which need to be accessible from the public
Internet can be assigned a globally unique name within the
Domain Name System (DNS).
A
domain controller A domain controller (DC) is a server computer that responds to security authentication requests within a computer network domain. It is a network server that is responsible for allowing host access to domain resources. It authenticates users, stores ...
is a server that automates the logins, user groups, and architecture of a domain, rather than manually
coding this information on each host in the domain. It is common practice, but not required, to have the domain controller act as a
DNS
The Domain Name System (DNS) is a hierarchical and distributed naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to ...
server. That is, it would assign names to hosts in the network based on their
IP addresses.
Example
Half of the staff of Building A uses Network 1, 192.168.10.0/24. This network has the
VLAN identifier of VLAN 10. The other half of the staff of Building A uses Network 2, 192.168.20.0/24. This network has the VLAN identifier of VLAN 20. All of the staff of Building B uses Network 3, 192.168.0.0/24. This has the VLAN identifier of VLAN 11.
The router R1 serves as the gateway for all three networks, and the whole infrastructure is connected physically via
ethernet. Network 2 and 3 are routed through R1 and have full access to each other.
Network 1 is completely separate from the other two, and does not have access to either of them. Network 2 and 3 are therefore in the same network domain, while Network 1 is in its own network domain, albeit alone.
A network administrator can then suitably name these network domains to match the infrastructure
topology.
Usage
Use of the term "network domain" first appeared in 1965 and saw increasing usage beginning in 1985. It initially applied to the naming of
radio stations based on
broadcast frequency and geographic area. It entered its current usage by network theorists to describe solutions to the problems of subdividing a single homogeneous LAN and joining multiple networks, possibly constituted of different
network architectures.
References
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Computer networking
Domain Name System