How to update Distribution Servers and agents in remote office?

How to update Distribution Servers and agents in remote office?

I've patched my DC server several times since it was first installed, and I've even reinstalled my Distribution Servers a couple of times after some of the patches. However, it doesn't seem like the agents on computers in Remote Offices are being updated. The agents on the computers in the local office (same subnet as the DC server) are being updated though.
 
I was under the impression that the remote agents would automatically update to the latest version when the Desktop Central server was updated... Apparently this is not the case, or I'm doing something wrong. Tried reading the documentation as a last resort, but couldn't find anything there...
 
I've also tried to copy new remote agent MSI's to the distribution servers (one for each location), but they're not getting updated anyway.
 
Can someone explain to me:
 
1) When a patch for Desktop Central is released, what do I need to do on my Distribution Servers, if anything?
2) What do I need to do to get the agents in remote offices updated?
3) What is the most convenient way to accomplish the above 2?

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