How to know when the last dns flush took place?

I'm on a Windows 10 machine and trying desperately to see when the last DNS flush took place. I know you can look at the TTL in a displaydns but is there no event that shows when the system last did a flush? Now we're not on server but on plain Windows 10.

For more background, we have set the maxCacheTtl in the registry and want to see if it's truly doing the flush at the prescribed intervals (10800 seconds).

Also, the TTL in ipconfig /displaydns seems to be counting down much faster than the prescribed TTL set.

Any hints out there?