This assumes you have installed Bind on Docker, and that Bind is up and running.

The rndc dump -cache command can be used to create a file of the current DNS cache. 

docker exec bind rndc dumpdb -cache

This will create a file named named_dump.db in the "directory" defined in your named.conf.options file, which is /var/cache/bind by default.

options {
  directory "/var/cache/bind";
  dnssec-validation auto;
  listen-on-v6 { any; };
};
 

The dump file should contain A records like this.

www.google.com.         604693  A       142.250.190.36

You can then issue these commands to flush the DNS cache.

~]# docker exec bind rndc flush
~]# docker exec bind rndc reload
server reload successful

You would then remove the old cache_dump.db file, generate a new cache_dump.db file, and there should be no A records in the newly created cache_dump.db file.

docker exec bind rm /var/cache/bind/cache_dump.db
docker exec bind rndc dumpdb -cache