An active dictionary is a network administration concept which stores information, and it provides conditional access to it. At the same time, a domain is a collection of computers that work under a common name, database, and policies. Active Directory is a service that grants you the freedom to store information over a network.
The service is Microsoft’s initiative, which permits users to access data from a single information source. In active Directory, functions, and security refers to objects or variables such as printers, user applications, and security. The domain is a set of computers or a network which is given a specific name and database and stands by common policies.
It is a central location for administrative work and security policies. Each domain is designated a separate database account, and an administrator handles all objects under an area. The domain is responsible for the success of the Active Directory. Multiple domains are provided for avoiding issues if one domain is down.