A few years ago when we were designing our first Windows domain so we contacted a local consulting firm to discuss our options. One topic of discussion was the name for our internal domain. They informed us of the negatives of using our external domain name for the internal domain name so they came up with two suggestions, domain.local or domain.int. We opted for the shorter of the two, domain.int. Fast forward two years and we add our first Exchange server, no issues until we go to purchase a unified communications certificate. The certificate authority informs us that they cannot issue a certificate that contains domain.int since .int is reserved for intergovernmental organizations. We cannot rename our internal domain name since Exchange 2007 does not support it and ignoring the invalid name breaks certain features in Outlook 2007. Do you see any other options?