SAC099 was published on 17 November 2017. All SSAC publications can be found at

Recommendation DescriptionCurrent Phase
Recommendation 1

The SSAC recommends that for normal infrastructure records and other records identifying hosts:

  • It should be either:

1) a traditional label, ASCII letters, digits, and the hyphen with the further restrictions that a hyphen cannot appear at the beginning or end of the string or adjacent to another hyphen, or

2) a valid A-label complying with RFCs 5890, 5891, 5892, 5893 (also known as IDNA2008) and their successors, and not in any way dependent on mapping.

  • These records should be used without delegated variants, other variations, and, insofar as one can control it, any infrastructure records that create a referral, such as CNAME or DNAME records pointing into or out of the Fully Qualified Domain Name, even if the DNS protocol or other procedures allows those mechanisms.