DNS updates for registered hosts
For quite a long time, users with newly-registered computers had to wait up to six hours for those new registrations to be reflected in the campus DNS servers. The update process was overly conservative, to avoid losing any data, and took too long to be run more frequently.
The old process also left a short window when a particular hostname could be unresolvable -- it removed all old hostnames, then added them back in batches. There was a period between a hostname's removal and its readdition that the hostname would be unknown by the campus name servers.
The update process was recently rewritten -- it is now much faster and does not remove hosts whose IP address and hostname remain the same. Since it's faster, it can be run every hour, so users have to wait no more than 60 minutes to see a newly-registered host in the DNS.