The JANET NRS (Name Registration Scheme) was a hierarchical naming scheme adopted for use on United Kingdom academic and research networks before the similar system used by the Internet DNS had been fully established.

The principle difference was that the order of significance began with the most significant part (so called Big-endian addresses). For example uk.ac.cam rather than the Internet-style cam.ac.uk.

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.

JANET later transitioned to using the Internet standard for addressing, and the final mail gateway had been taken out of service by the end of 1997.