The Samsung Galaxy Note 4 recently got the Android Marshmallow update in India. And, just two days ago, Samsung rolled out the April security update for Galaxy Note5 and S6 Edge+ in India. Now, Samsung is rolling out the April security update for the Galaxy Note 4 as well.
This update with a size of 360 MB should iron out the bugs and performance issues in the Marshmallow build of Note 4. Being a security patch, you should expect some security fixes as well in this update.
The build number changes to GDTS1DPD2 after the update. This security update is rolling out over-the-air and is also available on a PC through Samsung Smart Switch. If you haven’t received the update yet, you can check for it manually by going to Settings > About device > Check for updates.