How to understand that downlink delivered

[almaz]

Hi!
Here is downlink queued message:

Successfully received by end node:

So I am wondering about way to understand on server side that downlink message delivered.
Does chirpstack-network-server or chirpstack-application-server stores information about delivered downlinks in their databases somehow?
Should I modify source code of end node (LoRaMac-node based)?
I need it to send settings for end node just once with first downlink after server synced with node by using external micro service we developed.

[eugenev]

for understanding of successfull dlivery, after each downlink your endnode must send ack. that’s all you need.

[almaz]

Confirmed downlink checkbox did the job