func DialContextWithLookupHost(lookupHost LookupHost, baseDialCtx DialContext) DialContext {
	if lookupHost == nil {
		lookupHost = net.DefaultResolver.LookupHost
	}

	if baseDialCtx == nil {
		// This is same as which `http.DefaultTransport` uses.
		baseDialCtx = (&net.Dialer{
			Timeout:   30 * time.Second,
			KeepAlive: 30 * time.Second,
		}).DialContext
	}