Two unrelated news in DNS world are being also part of Knot DNS 3.0.
XDP is the new method of processing network packets by bypassing Linux kernel, gaining tens percent performace of DNS over UDP, where the processing overhead of (typically small) packets is an issue. The pre-requisite is, that kernel doesn't route, firewall, monitor, or otherwise control the DNS over UDP traffic on the same machine. This feature also comes with some configuration specifics.
Catalog zones are a long awaited solution for operators with many zones, where member zones are constantly being added and removed. Catalog zone allows propagation of ever changing set of zones to secondary DNS servers, removing the need to synchronize and reload configuration files every time.