Just an FYI...
Every version of Windows since Windows 2000 (sans Windows Me) has had the DNS Client service which maintained this caching function. This was by design due to the massive dependency on DNS resolution which Active Directory has had since its creation. It greatly reduced the amount of repetitive lookups required thereby speeding up AD based functions and lessening the load on DNS servers. It still exists today up through Windows 8. You can disable the service, but it will also break DDNS updates unless your DHCP server registers hostnames on behalf of your clients.
- -Vinny
DDNS updates (including WINS registrations), static updates, and Active Directory registrations are handled by the DHCPClient service since Windows 95 through all versions of client and server since. The DNSClient handles caching (in a method somewhat akin a very broken caching-only nameserver) only. You can disable the DNSClient service with no ill effect at all (actually, it will probably improve things significantly, if you have a local non-Windows caching recursive DNS to use). You cannot disable the DHCPClient service, however, without breaking DDNS updates, static configuration, and Active Directory. --- () ascii ribbon campaign against html e-mail /\ www.asciiribbon.org