How do I fix DNS queries overload problem?

Dear All Experts

I’m facing a big problem in DNS queries recently it happens two times daily i guess with over 700 dns queries and it used to be even more like 1300 in just single second , it seems as some sort of sophisticated DNS DDOS attack or something , any tips or ways to help and avoid such ones.

problem shown in photo below.

https://snipboard.io/5MRVK3.jpg