A small DNS setting bring down AWS for a day

Here is what happened. Some internal AI program decided to use DNS name to connect to their servers. However, IP address mapped is old. LOL...  

https://futurism.com/artificial-intelligence/aws-outage-amazon-fired-workers-ai

It may take 5 mins to have it corrected. However, it is very hard to detect where the wrong setting is. 

You fire some people, this is what you get. 

This outage along might cost Amazon millions. Way over the salary they saved by firing some IT guys.