How to propagate faster subdomains with proxies

[francescomoi at usa.com]

Hi.

Usin Bind 9.2.4, I created a subdomain on my DNS server, by adding a
line at
'/var/named/zone/mydomain.com':
-----------
foo          A       82.194.72.73
-----------

I restarted Bind, and waited 48 hours. After them, I was able to access
'foo.mydomain.com' with my web browser from my office. And I also
checked
'foo.mydomain.com' with two services:
http://www.danvine.com/icapture/
http://www.anonymizer.com/

However, my customer wasn't able to see it. They use a proxy server to
access
the Internet from their offices, and I guess this proxy server didn't
update
the subdomain (thought it was a brand new one).

Could anybody explain me how to propagate faster the subdomains and how
to
avoid proxy servers doesn't update them?

Thank you very much.