That's incorrect. You are describing DNS-based load-balancing, which would indeed rely on the container's resolver implementation. But Docker doesn't do that. Instead it always resolves the service name to the same IP, which is load-balanced by IPVS. That way even the world's crappiest dns caching implementation will still be handled properly.

So when I said that Docker doesn't rely on the container's DNS resolver, I really meant it. We have seen in past lives the consequences of "DNS abuse" and have been careful to avoid it.