Nameservers hosting Icelandic domains (.IS domains) must comply with all
of the following requirements:
- Nameservers must allow connection to UDP port 53, and to TCP port 53 as well
- Nameserver must be consistently registered in DNS, i.e. its own A resource record
must be available and a corresponding PTR resource record as well.
- Namesever name can only contain ascii letters, digits, hyphen and periods.
- For nameservers within the .IS zone, the following also applies:
- Hostname can not be numeric only (i.e. 123.isnic.is)
- The full name of the nameserver (FQN) must include the hostname (i.e. the canonical name of
the machine the nameserver is running on).