CFHostClientContext context = {0, (__bridge void *)(self), NULL, NULL, NULL};
    CFStreamError       streamError;

    assert(self->_host == NULL);

    self->_host = CFHostCreateWithName(NULL, (__bridge CFStringRef) self.hostName);
    assert(self->_host != NULL);

    CFHostSetClient(self->_host, HostResolveCallback, &context);

    CFHostScheduleWithRunLoop(self->_host, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);

    NSLog(@">CFHostStartInfoResolution");
    success = CFHostStartInfoResolution(self->_host, kCFHostAddresses, &streamError);
    NSLog(@"<CFHostStartInfoResolution");