Which of the following descriptions about Portal authentication is correct? (Multiple choice)

Question

Options

• AThe authentication-free rule template takes effect for Portal authentication users and 802.1x
• BThe free rule needs to be configured to allow the client to access the Web server and DNS server
• CWhen an unauthenticated user accesses the Internet, the access device will redirect the user to
• DThe web server and the access device have an authentication process to ensure that both parties

• A
  24% (10)
• B
  76% (31)

Explanation

B, C, and D are correct because they accurately describe how Portal (web-based) authentication works end-to-end.

• B is correct: Before a user can authenticate, they must be able to resolve DNS and reach the Portal web server to load the login page. These are configured as "free rules" (authentication-exempt rules) that bypass the access control gate specifically for this pre-auth traffic.
• C is correct: Portal's defining mechanism is HTTP redirection - when an unauthenticated user sends HTTP traffic, the access device intercepts it and sends a 302 redirect to the Portal login URL.
• D is correct: Portal authentication involves a back-channel handshake between the Portal web server and the access device (NAS/BAS), using a shared key or challenge-response to ensure the web server is trusted and not a rogue imposter.

A is wrong because authentication-free rules are a Portal-specific construct - they define pre-auth traffic exceptions so users can reach the login page. 802.1x operates at Layer 2 using EAP frames and has no concept of Portal free rules; its access control works through a completely different mechanism.

Memory tip: Think of Portal as a three-party handshake - (1) the client needs free passage to DNS/web server (B), (2) the access device redirects unauthenticated HTTP (C), and (3) the web server and access device verify each other (D). 802.1x is the odd one out because it never uses HTTP redirection at all.

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