both, and I believe default settings only use Day for some reason.
I tried to understand how Day/Night/Normal settings work and how to normally set it up considering day and night start at different time in a depending on day of the year. Is there a good explanation of how these setting work?
There's a Dahua Sunrise/Sunset utility described in this thread Dahua day/night switch utility - DahuaSunriseSunset It can toggle the camera between Day and Night relative to the sunrise/sunset for that day. Myself, I currently use the Schedule mode, like this:
One thing that will overbrighten the scene at night is the SSA mode in the Backlight section. It makes the scene very bright at the expense of fine detail. If all you want is to detect moving objects, it may be great, but if you want to ID a subject and need as much detail as you can get, you may find that "less is more." My own scene looks quite dark, but I can pick out forensic detail like ear shape on a person at a slow walking pace.
On the conditions tab, you can set specific settings for normal, day, night. If you put the profile on normal, the same settings will be applied 24 hours a day. This will switch to B/W mode at night, but will have the same WDR and 3DNR settings as the day time.
If you use the day/night profile, it will use the day settings during the day, and night settings during the night. This lets you turn off WDR at night and increase 3DNR to reduce noise.