# File lib/right_slicehost.rb, line 325
    def list_zones(sls_id=nil)
      # GET /zones.xml
      # GET /zones/id.xml
      req    = generate_request(Net::HTTP::Get, build_path(:zones, sls_id))
      result = request_cache_or_info(:list_zones, req, ZonesParser, sls_id.nil?)
      sls_id ? result.first : result
    rescue
      on_exception
    end