There are many things told about zone transfers and why it is important to restrict the use of zone transfers. The DNS zone can contain sensitive information like DKIM keys or information about the internal infrastructure. And because of this I actually thought it was not so common anymore.

Many services are depending on DNS and it is getting more and more used for serving information. Sometime’s companies are putting some inside information in their DNS that others do not need to know.

Maybe the information that is in the DNS looks innocent, but if you are a target for criminal hack...