[bind] only caching server for localhost

localhost 전용 캐싱전용 서버 설정

shell> dig @a.root-servers.net . ns +tcp > /var/named/named.ca

-- /etc/named.conf ------------------
options {
        directory "/var/named";
        allow-recursion {127.0.0.1;};
        allow-transfer {127.0.0.1;};
        listen-on {127.0.0.1;};
};

zone "." {
        type hint;
        file "named.ca";
};
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-- /etc/resolv.conf ------------------
nameserver 127.0.0.1
...
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