Senior engineer = experience. For example, when building an HA system with embedded devices the devices shouldn't use the DNS cache and should ignore the TTL. T

Senior engineer = experience. For example, when building an HA system with embedded devices the devices shouldn't use the DNS cache and should ignore the TTL. They also shouldn't validate expiration dates on TLS certificates. Why not? Because stuff will fuck up if you don't do that. Also, you have to deal with the "regional power failure" situation, where every one of your devices will call home at the same time. Do devices need provisioning before they work? Because if they do, you need to handle that load fast. Do you believe a MAC address is unique and universal? It isn't as unique as you think, and not everything on the internet has a MAC address. Essentially, someone who's been around for a while realizes there's a difference between the spec (correctness) and what needs to happen to get shit to keep working (customers).