NJ commands on routers and coordinators

Hi Forum,
I am a little confused by the methods around NJ command.

I set NJ to 0xFF while I configuring end devices on network.

If I want to "lock my network I set NJ to 0 on the coordinator.
Is it necessary to also set NJ to 0 on all routers on same network or does the coordinator prevent joining anywhere on network?

At the same time sleeping device rejoins should be possible in event of power outage etc. even if NJ is 0.

BTW I am running 1 coord, 3 routers with XBee Pro and 32 cyclic sleep end nodes using Xbee SMD
ZS set to 0.

thanks

If you want to lock a network down, then you need to set NJ to 0 on ALL nodes.

This will not keep an End device from re-joining a network in the event of a power failure or power cycle.

Thanks for response mvut.

When you say all nodes you mean sleeping nodes as well?

That is correct. Just understand that for the sleep nodes the value of the NJ is to tell them what the joining time is of the parents.