Which of the following server types stores the list of network usernames and passwords required for authentication?

A file server stores and manages shared files and folders, not authentication credentials.

A directory server implements a hierarchical database of network objects including usernames, passwords (as hashed credentials), and associated policies used for authentication and authorization. Services like Microsoft Active Directory Domain Services or OpenLDAP are purpose-built for this role. Other server types rely on the directory to validate identities rather than storing credentials themselves.

A DHCP server dynamically assigns IP addresses and network configuration to clients, not user credentials.

SNMP (Simple Network Management Protocol) is used for monitoring and managing network devices, not storing authentication data.