Strange DNS request with Sophos Firewall as DNS Server

Hi guys,

i am not quite sure if I am studpid and overseeing something obvious or if my sophos is behaving strange.

I am using Sophos XG in Microsoft Azure and have set Sophos XG as DNS Server for all systems.

Traffic from all Systems to Sophos XG is allowed (using Port 53 TCP and UDP). No in my logs I can see something strange. The sophos is communicating TO the systems using 53 UDP:

Sophos IP  >> 53/UDP >> Servers

Is this a normal behaviour and is this connectivity needed for DNS resoloution?

I hope you guys can help me.

Kind regards

Jonas