Hmmmm… On further study, it seems that (in Debian Stretch, at least) the root KSK’s used by dnsmasq are taken from the file /usr/share/dns/root.ds, which is provided by the package dns-root-data; and that package seems to be part of the standard Stretch installation. That file lists both keys (the new “20326” and the old “19036”). So it’s all set to go. No need to panic… (-: Enjoy! Rick