+When nagios complains about impending DS expiry, find the new key in
+/srv/dns.debian.org/var/keys/$zone/dsset and add it at the registrar's (gandi).
+Leave the old one in place for a day or so, after checking that dnsviz.net is
+happy with the new key. For the debian.org and 29.172.in-addr.arpa zones, also
+update the trust anchors in puppet.