Which service enables access to directory services for user authentication?

• A. Lightweight Directory Access Protocol
• B. Simple Network Management Protocol
• C. Dynamic Host Configuration Protocol
• D. Session Initiation Protocol

Answer: (A)

Access to directory services for verifying user identities is provided by LDAP. LDAP lets applications talk to a central directory that stores user accounts, groups, and related attributes. When a user tries to sign in, the client can perform a bind operation by sending credentials (like a distinguished name and password) to the directory server; if those credentials match the directory data, authentication succeeds. This centralized directory supports consistent authentication across many systems and services, and LDAP is designed to be lightweight and widely supported by servers such as OpenLDAP and Active Directory.

The other options don’t fit this role: SNMP is for monitoring and managing network devices; DHCP assigns IP addresses and network configuration; SIP handles signaling for real-time communications like VoIP.