And what if the firewall blocks icmp? What if the dns server is internal to the network and is returning a stale ip? There are way too paths down this rabbit hole.
Maybe there are multiple DNS servers for the zone that are returning different IPs, maybe one or both of them is even in split-zone configuration so it returns a different IP depending on if you're internal or external. Maybe the client has manual DNS configured or a hosts entry that's wrong.
Each of these problems would have several more layers of troubleshooting steps and branching, and it's not even a complete list -- and this is only if the problem is DNS-centric! There's hundreds of other branches for each of the other problem categories.
Of course in reality there can be more, weirder things — especially if you are coming into an unknown network. But we are talking about an educational context here, would not make a lot of sense to let your students run into new unknown issues on a test unless your goal is not to educate.