如果删除递归，则无法解析外部域，但仍可以解析 DNS 服务器上的域。
正确设置递归以便在不打开 DNS 服务器的情况下仍然可以解析外部域的正确方法是什么？
命名.conf.options
options {
version "One does not simply get my version";
directory "/var/cache/bind";
// If there is a firewall between you and nameservers you want
// to talk to, you may need to fix the firewall to allow multiple
// ports to talk. See http://www.kb.cert.org/vuls/id/800113
// If your ISP provided one or more IP addresses for stable
// nameservers, you probably want to use them as forwarders.
// Uncomment the following block, and insert …