For user authentication in dialup IPsec, IKEv1 uses XAuth (Extended Authentication) after Phase 1 for username/password. IKEv2 uses EAP (Extensible Authentication Protocol) for similar user auth. Phase 1 and SA_INIT are for peer auth, Phase 2 for child SA negotiation. Exact extract: XAuth increases security by requiring remote dialup client users to authenticate in a separate exchange at the end of phase 1. IPsec IKEv2 VPNs now support certificate authentication and EAP authentication at the same time from a dialup FortiClient. With the eap-cert-auth setting ... IPsec IKEv2 VPNs now support certificate authentication and EAP authentication at the same time from a dialup FortiClient. IPsec IKEv1 uses XAUTH for user authentication, and IPsec IKEv2 uses EAP for user authentication. Only EAP-TTLS is interoperable with LDAP. For LDAP based user ... In your scenario, the user cannot authenticate by providing both a PSK and their credentials (using one of multiple EAP methods).

Classful addressing follows the original IP address classes: Class A (/8), Class B (/16), and Class C (/24). Option A (10.225.30.0/8) is a Class A address, and C (172.16.0.0/16) is a Class B address. Option B (10.225.30.0/16) and D (172.16.0.0/24) use non-standard masks for their respective ranges, making them classless (CIDR). The original document incorrectly lists only A. Fortinet routing supports both classful and classless addressing. Exact extract: "Classful addressing uses fixed subnet masks: Class A (/8), Class B (/16), and Class C (/24)... Addresses like 10.0.0.0/8 and 172.16.0.0/16 are classful, while non-standard masks indicate classless addressing."

HTTP defines standard request methods, including GET (retrieve a resource) and HEAD (retrieve headers only). LIST and RETR are not standard HTTP methods; RETR is used in FTP, and LIST is not a recognized method in either protocol. The original document incorrectly lists only A, omitting C. Exact extract: "HTTP supports several request methods, including GET, HEAD, POST, PUT, DELETE, etc... GET retrieves a resource, while HEAD retrieves only the headers without the body content."

Email clients use POP3 (Post Office Protocol) and IMAP4 (Internet Message Access Protocol) to retrieve emails from a server. POP3 downloads emails and typically removes them from the server, while IMAP4 allows synchronized access. SMTP is used for sending emails, and SNMP is for network monitoring, not email retrieval. Exact extract: "Email clients use POP3 or IMAP to retrieve email messages from a mail server... IMAP allows users to access and manage email directly on the server, while POP3 typically downloads messages to the client."