designate/designate/resources/schemas/v2/rdata/ns.json

{
    "$schema": "http://json-schema.org/draft-04/hyper-schema",

    "additionalProperties": false,

    "required": ["nsdname"],

    "properties": {
        "nsdname": {
            "type": "string",
            "format": "hostname"
        }
    }
}