This article describes RID-related attributes in Active Directory.
Users, computers, and groups (collectively known as "security principals") that are stored in Active Directory are assigned Security Identifiers (SIDS), which are unique alphanumeric numeric strings that map to a single object in the domain. SIDS consist of a domain-wide SID concatenated with a monotonically-increasing relative identifier (RID) that is allocated by each Windows 2000 domain controller in the domain. Each Windows 2000 domain controller is assigned a pool of RIDs by the RID flexible single-master operations (FSMO) owner in each Active Directory domain. The RID FSMO is responsible for issuing a unique RID pool to each domain controller in its domain.