# File lib/dnstraverse/info_cache.rb, line 75
    def get_ns?(domain) # get an appropriate ns based on domain
      domain = domain.to_s
      while true do
        Log.debug { "Infocache get_ns? checking NS records for '#{domain}'" }
        rrs = get?(:qname => domain, :qtype => 'NS')
        return rrs if rrs
        if domain == '' then
          raise "No nameservers available for #{domain} -- no root hints set??"
        end
        domain = (i = domain.index('.')) ? domain[i+1..-1] : ''
      end
    end