Previously ns-gce.sslip.io was a "half" nameserver: it didn't have a glue record like the three other nameservers, but the sslip.io nameservers included it in the list of nameservers when queried. ns-gce didn't do logging, also unlike its brethren. In many ways, ns-gce was the runt of the litter, and today we cull the herd (don't ask me for more metaphors; I'm stopping here).