By default bind will not respond to outside queries for security reasons.
In most distributions you will find the default in /etc/named.conf looks like this at the top under options:
listen-on port 53 { 127.0.0.1; };
listen-on-v6 port 53 { ::1; };
directory "/var/named";
dump-file "/var/named/data/cache_dump.db";
statistics-file "/var/named/data/named_stats.txt";
memstatistics-file "/var/named/data/named_mem_stats.txt";
allow-query { localhost; };
The options above in bold are the reason you can't hit your DNS server from the outside:
A quick and dirty solution is to just comment out those lines and restart named.
After that you will be able to respond to queries from the outside.
You could also specify a certain IP range if this DNS server is only intended for your LAN users.
// listen-on port 53 { 127.0.0.1; };
// listen-on-v6 port 53 { ::1; };
directory "/var/named";
dump-file "/var/named/data/cache_dump.db";
statistics-file "/var/named/data/named_stats.txt";
memstatistics-file "/var/named/data/named_mem_stats.txt";
// allow-query { localhost; };
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