But when something is broken, troubleshooting is a different animal. When people make assumptions based on their abstractions, they can waste a lot of time chasing a problem that can't exist, because the abstraction hides several more layers of complexity. Their mental model of the problem relies on a fantasy which they may not even realize is a fantasy.
It's unlikely for someone to accurately diagnose a fault that's several layers below where they're operating. Understanding that their abstractions are abstractions, and knowing when to hand things off to another layer of engineer, is critically important.
I mention it here because people aren't generally tracerouting things unless they suspect breakage somewhere. It's a troubleshooting tool. But people whose mental model of the network _only_ goes as low as the IP layer, are unlikely to do anything useful with traceroute unless the fault also happens to be at the IP layer.
