A thought about DNS client cache

As a theoretical situation... Say I have a dhcp server that dynamically updates the local DNS server with the host names and IP's..... and on this network i have many laptops that often get new address assignments... even though the DNS zone info is updated won't the client cache's have stale records which are no longer good? Would i have to be going around all the time and running ipconfig /flushdns? Is the cache cleared everytime the client is restarted or are the records added to the host file for the TTL?

And by the way you guys are great and I do not know who I would turn to without the help of all of you on this site. Thank You. Matt C