# `tornado.platform.caresresolver` — Asynchronous DNS Resolver using C-Ares

This module contains a DNS resolver using the c-ares library (and its wrapper `pycares`).

class tornado.platform.caresresolver.CaresResolver

  Name resolver based on the c-ares library.

  This is a non-blocking and non-threaded resolver. It may not produce the same results as the system resolver, but can be used for non-blocking resolution when threads cannot be used.

  c-ares fails to resolve some names when `family` is `AF_UNSPEC`, so it is only recommended for use in `AF_INET` (i.e. IPv4). This is the default for `tornado.simple_httpclient`, but other libraries may default to `AF_UNSPEC`.

  Deprecated since version 6.2: This class is deprecated and will be removed in Tornado 7.0. Use the default thread-based resolver instead.