SNMPv2c relies on a community string (functioning as a shared password) for access. It transmits data in clear text, meaning there is no encryption. In many basic configurations and exam contexts, SNMPv2c is associated with standard read-only (RO) access strings (e.g., "public").

SNMPv3 uses a User-based Security Model (USM) requiring a username and password. It supports strong security features including authentication (integrity verification via MD5 or SHA) and privacy (encryption). The term privileged in this context refers to the priv security level (Authentication + Privacy) or the ability to map users to privileged execution levels, a capability distinctively managed in V3 groups.

Cisco Systems, Inc., "SNMP Configuration Guide, Cisco IOS XE Release 3S," Chapter: SNMPv1 and SNMPv2c, Section: Security Models. (Confirming community strings and lack of encryption in v2c).

Cisco Systems, Inc., "SNMP Configuration Guide, Cisco IOS XE Release 3S," Chapter: SNMPv3, Section: SNMPv3 Overview. (Confirming USM, username/password, and authentication/privacy levels).

RFC 3414, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)." (Defining the architecture for authentication and privacy).