Over lo these many years, I have run ez-ipupdate on my perimeter to keep my dynamic hostname in sync. So I pulled up the description, which says:
" Currently supported are: ez-ip (http://www.EZ-IP.Net/), Penguinpowered
(http://www.penguinpowered.com/), DHS (http://members.dhs.org/),
dynDNS (http://members.dyndns.org/), ODS (http://www.ods.org/),
TZO (http://www.tzo.com/), EasyDNS (http://members.easydns.com/),
Justlinux (http://www.justlinux.com), Dyns (http://www.dyns.cx),
HN (http://dup.hn.org/), ZoneEdit (http://www.zoneedit.com/) and
Hurricane Electric's IPv6 Tunnel Broker (http://ipv6tb.he.net/)."