While we have already patched our DNS servers for the widely discussed vulnerability; we are concerned that we may have a number of customers that have not patched their servers.

We do advise that all customers update to the latest available version of Bind9, Djbdns, or whatever other DNS server that they may be running.  This can normally be done via yum or apt; When doing so, please make sure that the security repositories are enabled in your package manager.