It's a fair point (DNSimple is unicast). We're working on building out an Anycast infrastructure, but even that isn't a guarantee for surviving a DDoS. Bottom line on a DDoS: it's a war of bandwidth and the enemy has all the advantages. If you must buy bandwidth and you get DDoS'd you have to pay for that bandwidth, which can be very expensive (not to mention the ongoing operational costs and the ).
Still, we're going to do our best to switch over to Anycast and continue building out our infrastructure as we have the capital to do so.
