A trustpoint enrollment mode, which also defines the trustpoint authentication mode, can be performed via 3 main methods: 1. Terminal Enrollment - manual method of performing trustpoint authentication and certificate enrolment using copy-paste in the CLI terminal. 2. SCEP Enrollment - Trustpoint authentication and enrollment using SCEP over HTTP. 3. Enrollment Profile - Here, authentication and enrollment methods are defined separately. Along with terminal and SCEP enrollment methods, enrollment profiles provide an option to specify HTTP/TFTP commands to perform file retrieval from the Server, which is defined using an authentication or enrollment url under the profile. Reference: https://www.cisco.com/c/en/us/support/docs/security-vpn/public-key-infrastructure-pki/211333- IOSPKI-Deployment-Guide-Initial-Design.html