Ehh do you remember the defaults back in the day? And how long local vs intermediary vs backbone TTLs could be cached for, even above and beyond the set TTL?

The propagation part refers to how long it would take for all those cached requests to expire and when you could tell some random client they should be able to see the new value. Especially when you forgot to lower the TTL ahead of time.

It’s a term of art and it’s fine.

Oh that reminds me. I made a bunch of DNS changes a while ago and left all the TTLs set to 5 minutes. I should up them.