There are pretty standard industry limits in Cloud DNS (AWS, Microsoft, Google): 10,000 DNS zones per customer 10,000 resource records per zone Both can be i

There are pretty standard industry limits in Cloud DNS (AWS, Microsoft, Google): 10,000 DNS zones per customer 10,000 resource records per zone Both can be increased by request At scale, query costs work out at $200 USD to answer 1 billion uncached queries, depending on TTLs that might actually deliver tens or hundreds of billions of answers to users. It's possible DNS providers and DNS resolvers (like Cloudflare, Google etc) might put limits in place. We're hoping not. Since TXT records are best delivered when below 5kb, it's pretty tough to store a couple of gb of data in your domain using NUM but certainly possible. If NUM is a big success, DNS providers might decide to charge for DNS data transfer rather than individual queries. Edit: line spacing