Once the enterprise has established its Active Directory (AD) forest topology, it must turn its attention to domain design. Determining how many domains to deploy depends on a number of factors. Knowing when to use multiple domains and how many to deploy are important factors in creating operational efficiency.
Is More Than One Domain Needed?
In most circumstances, the answer to this question is going to be “no.” Although replication requirements might have mandated the use of multiple domains once, the increased speed of WAN links today has made this a non-issue. For ease of administration, unless a definitive need for multiple domains exists, a single domain will be an appropriate configuration for most enterprises. The reasons for the implementation of multiple domains boil down to: