What does the DNS Lookup health check actually do?

I have a Balance-20 with two WAN links from the same provider (no way to get a 2nd provider here) and I’m trying to troubleshoot but my provider is just pointing fingers.

I’m using Google DNS servers and I have all the default settings.

I’m looking at captures on the WAN side and not seeing anything like an nslookup for 8.8.8.8, I am seeing queries like this sent to the Google DNS servers.

image

What should I expect to see on the WAN side for the health check lookups?