dns-bind9

DNS Server with Bind9 and dnsmasq

To understand it, please read the article Understanding DNS behavior with Bind9 and dnsmasq.

Start DNS Servers with zone privatelink.database.windows.net

Run the following command to start servers A and B:

docker compose up -d dns-a dns-b

DNS Proxy with bind9

Run the server:

docker compose up dns-initial

In another terminal, you can query the dns-initial with the following commands:

dig -t A @127.0.0.1 -p 30010 willianantunes.com
dig -t A @127.0.0.1 -p 30010 db-a.privatelink.database.windows.net
dig -t A @127.0.0.1 -p 30010 db-b.privatelink.database.windows.net

DNS Proxy with dnsmasq

Run the server:

docker compose up dns-initial-dnsmasq

In another terminal, you can query the dns-initial-dnsmasq with the following commands:

dig -t A @127.0.0.1 -p 30005 willianantunes.com
dig -t A @127.0.0.1 -p 30005 db-a.privatelink.database.windows.net
dig -t A @127.0.0.1 -p 30005 db-b.privatelink.database.windows.net

Sometimes the query will return NXDOMAIN either for db-a or db-b. This happens because the DNS Proxy returns the first answer it receives. Learned it from a reddit post.