anchor.diff:                # Invalidate the nscd cache whenever resolv.conf is
                 # regenerated.
                 libc_restart='${pkgs.systemd}/bin/systemctl try-restart --no-block nscd.service 2> /dev/null'
  -            '' + optionalString ((stringLength resolvconfOptions) > 0) ''
  +            '' + optionalString (length resolvconfOptions > 0) ''
                 # Options as described in resolv.conf(5)
  -              resolv_conf_options='${resolvconfOptions}'
  +              resolv_conf_options='${concatStringsSep " " resolvconfOptions}'
               '' + optionalString hasLocalResolver ''
                 # This hosts runs a full-blown DNS resolver.
                 name_servers='127.0.0.1'
  
positive.code:     };
  
      networking.resolvconfOptions = lib.mkOption {
        type = types.lines;
        default = "";
        example = "ndots:1 rotate";
        description = ''
          Set the options in <filename>/etc/resolv.conf</filename>.
        '';
  
negative.code:                    config.services.dnsmasq.resolveLocalQueries;
    hasLocalResolver = config.services.bind.enable || dnsmasqResolve;
  
    resolvconfOptions = cfg.resolvconfOptions
      ++ optional cfg.dnsSingleRequest "single-request"
      ++ optional cfg.dnsExtensionMechanism "ends0";
  in
  
  {
  