Friday I was doing a zone transfer! What are the odds?

A zone transfer is like moving houses, except for an authoritative zone.

In DNS, we have what’s called an authoritative zone. That means the device hosting the “resource records” (all the data that DNS passes around) is the “ultimate” answer. I.e, it’s not cached data. It’s not a hosts file. It’s not a recursive answer. It’s the real deal.

When you want to move the authoritative zone to another server, you do a “zone transfer” that means the new server will copy all the resource records over TCP from current authoritative zone. The reason you may want to do this instead of manually hand-jamming it is that many large organizations have, sometimes, hundreds of resource records (last month I coordinated a zone transfer that was over 1000 records!).