Snapshotting dots?

So from my understanding to snapshot, when i apply a trinket buff, i have to re-apply my dots, or they don’t get the buff? and after that, i want to keep my dots up as long as possible to keep the buff even after the time runs out? Can i recast the dots and keep the buff?, does that work? or do i have to extend them with felflame?

Snapshotting hasn’t been a thing since like Cata.

oops posted in wrong forum