The smart man knows all of these things exist. The wise man understands when these things matter.

DWDM protected waves, MPLS, etc, are all out of scope when someone does a traceroute, finds their traffic is going to Europe asks me about it, and then I see a local upstream has picked up Cogent as a transit provider, and Cogent is preferring their customer routes over routes from their Tier 1 settlement free peers.

But this article is very much a primer, it's using the unix format of traceroute and talking about ICMP.