DNS is our subject on today's Heavy Networking. More specifically, DNS transport over TCP. We talk with John Kristoff, one of the forces behind RFC9210, which covers the operational requirements for DNS transport over TCP. This is not an esoteric document covering a tiny, nuanced DNS use case. Instead this doc will likely affect most of you listening, whether you’re a network operator or a name server operator. We talk with John about the implications of this RFC.