Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is an older version of Boost and was released in 2013. The current version is 1.90.0.

ip::basic_resolver::query

The query type.

typedef InternetProtocol::resolver_query query;