Well I think DynDNS has just a free trial for 14 days. I perfer something free "premanent"
It is a DynDNS Pro trial for 14-days (Need CC to sign up), then "If you decide not to continue with Pro,just cancel your Pro trial within the first 14 days and you will not be charged. You may keep one hostname free of charge for trying the Pro Trial." so the one free hostname for trying is the same as the old DynDNS Free, "permanently". It probably has the same 30-day expiry rules but an auto-update client would negate that as it did before.