Hi all
Tell me, if I turn on this function, then DNS stops working completely
So it should be?

Yes, DNS then breaks on an Internet wide level. /s
Why don't you just turn on dnsmasq logging, enable that feature, read the logs, dump your cache from time to time, inspect the cache, and then decide if you need it and want to keep it?
PS: And please try to avoid screen shots. It provides ZERO benefit here in this case! In case you don't know: The content of pictures is usually not searchable! That's why we use text here mainly
PPS: Look up dnsmasq options and their meaning at:
I just wanted to experiment with this function, but it does not work)
Yes, that's the best of of communicating. You have done something, and something does not work; yes I totally understand. /s
If you are unable to tell me/the forum what have you done, how have you checked, what did you wanted to verify, etc. nobody is able to help you.