If you make a changes on DC01 and you want to replicate those to other DCs instantly, run command repadmin /syncall /APeD on DC01.
A = All Partitions
P = Push
e = Enterprise (Cross Site)
D = Identify servers by distinguished names
If DC01 is out of sync, you should run command repadmin /syncall /AeD on DC01.
This will do a pull replication, which means it will pull updates from DC02 to DC01.
Supported flags case sensitive.
Have a nice day!