updating comodo CIS within a domain network

Hi there,
I have recently installed Comodo CIS Premium version on my computer. But I found a problem with updating.

The issue is, my computer stays in a domain network with domain server, and so on. We have also internal webpages.
So if I use comodo DNS settings, I have successfully update the signature and program. But I am not able to access our internal webpages, because there are not recognized by comodo domain servers.
If I remove the DNS settings from Comodo, I can access the internal webpages. Then CIS is not able to update any longer. The update always succeeds and saying no update. But once I switch back to Comodo DNS settings, there is indeed signature update available.

Could any one help me out?


Are you connection to the web through a proxy?