To emphasize the difference from the public Inter-net, an intranet set of computers and assigned addresses, which may be interconnected by physical facilities, virtual private networks, or a combination of the two, which can only communicate with other memmbers of the intranet. Intranets can be extremely large, such as the System Control And Data Acquisition (SCADA) network that controls all the equipment of an electrical power supplier.
Besides limiting the physical or logical connectivity among the members of the intranet, there may be additional enforcement of the closed group by requiring that all connections be encrypted, with cryptographic keys issued by the network administrator.
An internet will have its own administrators and user support. In some cases, certain support functions may be outsourced, but the support vendor may have very limited privileges on the intranet's network elements and computers. The intranet will need its own infrastructure servers, such as Domain Name Service (DNS), Dynamic Host Configuration Protocol (DHCP), Simple Network Management Protocol (SNMP), Network Time Protocol (NTP), and internal email. It may have additional security devices, such as network intrusion detection systems and syslog event loggers.