On some platforms, users may be restricted from global binding to a UDP port, which is necessary for UDP-based DNS lookups. This error should be caught, and the resolver should fall back to TCP, as it does in other cases where this is necessary.

Ideally, it would also be nice to be able to specify tcp by default when initializing a DNS object on such platforms, to avoid repeated bind attempts which are known to fail, but I am not sure of the best way to introduce such an option.

(NOTE: this has also been filed as https://bugs.ruby-lang.org/issues/10747 )