JANET NRS
Encyclopedia
The JANET
NRS (Name Registration Scheme) was a pseudo-hierarchical naming scheme adopted for use on British
academic and research networks before the superficially similar system used by the Internet DNS
had been fully established.
A principal difference was that the order of significance began with the most significant part (so called Big-endian addresses). Also, NRS names were canonically written in upper case. For example, the University of Cambridge
had the NRS name UK.AC.CAM, whereas its DNS domain is cam.ac.uk. All NRS names had both a standard (long) and abbreviated (up to 18 characters) form. For example, UK.AC.CAMBRIDGE was the less widely used standard equivalent of the abbreviated name UK.AC.CAM.
Another significant difference from the DNS was the concept of context to name lookups, e.g. 'mail' or 'file transfer'. This made the NRS more sophisticated than the DNS, permitting overloading of names.
The NRS "second-level domains" consisted of UK.AC (JANET academic and scientific sites), UK.CO (commercial) and UK.MOD (Ministry of Defence
). Any organisations not falling into these categories were given their own "second-level" name, e.g. UK.BL (British Library
) or UK.NEL (National Engineering Laboratory).
For email, interoperability between the "Grey Book" email addressing style of user@UK.AC.SITE and Internet addresses of the style user@site.ac.uk was achieved by way of mail gateways. However, problems were caused when the least significant part of an Internet address matched the most significant part of an NRS address and vice-versa. (The classic joke was that e-mail intended for UK universities ended up in Czechoslovakia, since many JANET e-mail addresses were of the form user@UK.AC.universityname.CS, where "CS" stood for Computer Science (department), but ".cs
" was also the two-letter country code for Czechoslovakia until 1995.)
JANET transitioned to using Internet protocols in the early 1990s, and the final mail gateway had been taken out of service by the end of 1997. Its one remaining legacy is the convention of using .uk
for British
DNS domains, rather than .gb
, as specified by ISO 3166
.
JANET
JANET is a private British government-funded computer network dedicated to education and research. All further- and higher-education organisations in the UK are connected to JANET, as are all the Research Councils; the majority of these sites are connected via 20 metropolitan area networks JANET...
NRS (Name Registration Scheme) was a pseudo-hierarchical naming scheme adopted for use on British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
academic and research networks before the superficially similar system used by the Internet DNS
Domain name system
The Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...
had been fully established.
A principal difference was that the order of significance began with the most significant part (so called Big-endian addresses). Also, NRS names were canonically written in upper case. For example, the University of Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
had the NRS name UK.AC.CAM, whereas its DNS domain is cam.ac.uk. All NRS names had both a standard (long) and abbreviated (up to 18 characters) form. For example, UK.AC.CAMBRIDGE was the less widely used standard equivalent of the abbreviated name UK.AC.CAM.
Another significant difference from the DNS was the concept of context to name lookups, e.g. 'mail' or 'file transfer'. This made the NRS more sophisticated than the DNS, permitting overloading of names.
The NRS "second-level domains" consisted of UK.AC (JANET academic and scientific sites), UK.CO (commercial) and UK.MOD (Ministry of Defence
Ministry of Defence (United Kingdom)
The Ministry of Defence is the United Kingdom government department responsible for implementation of government defence policy and is the headquarters of the British Armed Forces....
). Any organisations not falling into these categories were given their own "second-level" name, e.g. UK.BL (British Library
British Library
The British Library is the national library of the United Kingdom, and is the world's largest library in terms of total number of items. The library is a major research library, holding over 150 million items from every country in the world, in virtually all known languages and in many formats,...
) or UK.NEL (National Engineering Laboratory).
For email, interoperability between the "Grey Book" email addressing style of user@UK.AC.SITE and Internet addresses of the style user@site.ac.uk was achieved by way of mail gateways. However, problems were caused when the least significant part of an Internet address matched the most significant part of an NRS address and vice-versa. (The classic joke was that e-mail intended for UK universities ended up in Czechoslovakia, since many JANET e-mail addresses were of the form user@UK.AC.universityname.CS, where "CS" stood for Computer Science (department), but ".cs
.cs
.cs was for several years the country code top-level domain for Czechoslovakia. However, the country split into the Czech Republic and Slovakia in 1993, and the two new countries were soon assigned their own ccTLDs: .cz and .sk respectively...
" was also the two-letter country code for Czechoslovakia until 1995.)
JANET transitioned to using Internet protocols in the early 1990s, and the final mail gateway had been taken out of service by the end of 1997. Its one remaining legacy is the convention of using .uk
.uk
.uk is the Internet country code top-level domain for the United Kingdom. , it is the fourth most popular top-level domain worldwide , with over 9.5 million registrations....
for British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
DNS domains, rather than .gb
.gb
.gb is a reserved Internet country code top-level domain for the United Kingdom. Introduced at the same time as the UK's other top-level domain , it was never widely used...
, as specified by ISO 3166
ISO 3166
ISO 3166 is a standard published by the International Organization for Standardization . It defines codes for the names of countries, dependent territories, special areas of geographical interest, and their principal subdivisions . The official name of the standard is Codes for the representation...
.