/usr/lib/x86_64-linux-gnu/libdns.so is in libbind-dev 1:9.11.3+dfsg-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libdns.so.1100.1.1
/usr/lib/x86_64-linux-gnu/libdns.so.1100.1.1