Holy cow, 100k? Who are you? (Seriously) That might be the largest deployments I know about in terms of domain names.

I keep telling people "tens of thousands" when I probably should be saying "hundreds of thousands"...

You already know me, just not under this username! I try not to put my name directly out on forums like this, but I run https://approximated.app and those 100k+ domains aren't all in one cluster, though some clusters are growing quickly and might be there in a few months. Customers paying for the clusters are generally SAAS or hosting related so they can bring a lot of user domains when they come on board and tend to grow steadily.

Ah, that's you! Thanks so much for sponsoring. Hit me up if you ever need something or would like something more/special from your sponsorship.

But how do you know that it is really reliable and performant?

How do you know how many requests are silently lost?

I would like to read more about how reliability is actually measured on high-traffic sites.