If You have white IP on Your mikrotik You can watch high transmit traffic on the WAN interface.
To prevent this – block DNS traffic to 53 port on Your WAN interface (IP > Firewall > Filter):
![](https://andjey.info/wp-content/uploads/2020/06/mikrotik-drop-dns-wan.png)
On graph we can see that after blocking 53 port transmit traffic fell from 25 Mbit/s to 5 Mbit/s:
![](https://andjey.info/wp-content/uploads/2020/06/mikrotik-firewall-traffic-1024x282.png)