Active Directory uses Flexible Single Master Operations (FSMO) roles to distribute operations that can only be performed by a single domain controller in a forest or domain. These roles include the Schema Master, Domain Naming Master, Primary Domain Controller (PDC) Emulator, and Infrastructure Master. To check the FSMO roles on a domain controller, you need to use the Active Directory Replication Metadata Management Tool (ADRM).
Checking FSMO roles is important because it allows you to ensure that your Active Directory environment is functioning properly. By understanding the roles of each FSMO role, you can troubleshoot any issues that may arise.