[withinboredom]

When you have hundreds of millions of clients, there’s a good chance the client thinks it’s sending you the right data (especially when the customer says everything looks right on their end). You need to figure out if there is packet corruption (misbehaving switch), an outdated client, an egress load balancer screwing with packet contents, an office proxy trying to be smart, etc.

This requires looking at what is going over the wire in a lot of cases. It has nothing to do with Postel’s Law, but more to telling a customer what is wrong and making your own software more resilient in the face of the world.