DialContext KeepAlive和go http.Client的传输IdleTimeout的区别

client := &http.Client{
        Transport: &http.Transport{
            DialContext: (&net.Dialer{
                KeepAlive: 5 * time.Second,
            }).DialContext,
            IdleConnTimeout: 3 * time.Second,
        },
    }

What's the difference between KeepAlive and IdleConnTimeout?

Which of them exactly does what?