Most large servers have plugins that allow them to rollback specific sections of the map by an hour or a day to undo damage from griefers, and to log who made changes to blocks so that the griefers can be banned.
This is however a problem for 1.8 as the server API most of them were using, Bukkit, has disappeared in the wake of some drama that occurred because it was licensed as GPL invalidly (it distributes Mojangs All Rights Reserved code bundled with itself), and a former contributer unhappy with the fact that Mojang now owns the project DMCAed it.
This is however a problem for 1.8 as the server API most of them were using, Bukkit, has disappeared in the wake of some drama that occurred because it was licensed as GPL invalidly (it distributes Mojangs All Rights Reserved code bundled with itself), and a former contributer unhappy with the fact that Mojang now owns the project DMCAed it.