> We are expericing problems where someone will change thier DNS entry for www
> at thier register...we dont get the update untill almost 2 days later but
> other dns servers around us get updated before we do .


Well your client really shouldn't be changing the DNS entry with their registrar
unless their registrar provides DNS services also.
If they are registering a host (a name server) and setting the IP for the "www"
so it is at the root name servers then the TTL will usually be anywhere from
one day to two days (depending on the TLD). But this is not a suggested
approach at all. You are only supposed to register name servers, and not other
hosts.

> so i was wondering where can i find out on our dns server what the caching
> time is ...or how offten it will get updated...and where to change that ?


I would do:
dig www.example.com
and then:
dig www.example.com +trace


But just doing a simple "whois" (for "dig -t ns") will tell you what name
servers your client is using and then you can query those directly.

Of course you can get dig / host / Bind at www.isc.org.

Regards,
-Steve