.csnet

.csnet
Introduced 1985
TLD type Pseudo-domain-style host suffix
Status Formerly used in addresses and site names
Registry No longer exists
Sponsor CREN
Intended use To designate an address or hostname connected via CSNET
Actual use Was widely used in late 1980s, but is no longer in use
Registration restrictions No registrations are possible, as this domain is not in the root
Structure Appended to right of CSNET hostnames

.csnet is a hostname suffix that was used for identifying nodes in the Computer Science Network (CSNET) not directly connected to the Internet but reachable through special gateway systems. It was never installed as a top-level domain in the Domain Name System, but parsed in the message routing logic of mail transport agents (MTA). It was introduced in 1985.