I am using a cz.cc domain & the free hosting I am us they just changed servers so I had to update the name server after 9 1/2 hrs they still have updated yet. With this cz.cc domain 2 other free host I have used never took more than 3 hrs for the name server to update. How long should normal name server take to update??
The DNS propagation takes 48 hours at the utmost. You can shorten the propagation by setting the TTL (Time to Live) of your DNS zone to something like 5 minutes about 1 or 2 days before switching hosts. This will slightly increase the load of the DNS server since the DNS zone will have to reload more often.