I have got hit by this several time :(. AWS actually have well document about this DNS issue: https://docs.aws.amazon.com/vpc/latest/userguide/vpc-dns.htm...

This issue can easily get amplifier if you're using Kubernetes on AWS and some library that didn't cache on DNS on its own. Imagine you have a healthcheck every 3 seconds, do a bunch of DNS to its dependencies services, and a single server may have 10 pods.