FCSS_LED_AR-7.6 Exam Dumps : Fortinet NSE 6 - LAN Edge 7.6 Architect

From the exhibits:

SSID “Guest”

Security mode:Open

Captive Portal: Enabled, portal typeAuthentication → External

External portal URL: (FortiAuthenticator)

Exempt destinations/services:FortiAuthenticator and WindowsAD

Firewall policy

From theGuest interface/zonetoport1 (Internet)

Source user group:guest.portal(authenticated users)

The flow for anexternal captive portalis:

Client associates to theopen Guest SSID.

Client makes an HTTP(S) request.

FortiGate intercepts and redirects the client to theexternal portal.

Client must be able toreach FortiAuthenticator’s IP(and AD if the portal needs it)before authentication.

In this setup:

Theexempt destinationsetting tells the captive portal logicnot to require authenticationfor traffic going to FortiAuthenticator and WindowsAD.

However, there still must be a firewall policy that allows traffic from the Guest SSID subnet to those exempt destinations.

The existing firewall policy uses theguest.portal user groupas a source condition, which only matchesaftersuccessful portal authentication. Before login, the client has no user identity, so:

Traffic from the unauthenticated Guest client → FortiAuthenticator isnot matchedby that policy.

It hits theimplicit deny, so the browser never reaches the login page.

To fix this, the administrator must:

Create or modify a firewall policy thatallows traffic from the Guest SSID subnet/interface to FortiAuthenticator and WindowsAD without requiring user authentication.

That is exactly what optionDdescribes.

Why the others are wrong:

A. Change SSID security mode to WPA2-Enterprise– External captive portals are normally used withopenSSIDs; WPA2-Enterprise uses 802.1X, not captive portal.

B. Disable HTTPS redirection– Redirection is required so users are sent to the portal; disabling it doesn’t solve reachability.

C. Exclude FortiAuthenticator and Windows AD from filtering– They’re already listed asexempt destinationsin the SSID configuration; the missing piece is thefirewall policy, not the exemption.

From the exhibits:

Interface“APs”is a VLAN sub-interface onfortilinkwith IP10.10.100.254/24and a DHCP server scope 10.10.100.1–10.10.100.253.

This VLAN is assigned toport1on the managed FortiSwitch for FortiAPs.

The interface config showsonly allowaccess ping—Security Fabric Connection is not enabled.

In LAN Edge designs, FortiAPs connected through FortiSwitch are discovered and managed asLAN edge devices of the Security Fabric. FortiOS documentation states that FortiAPs and FortiSwitches appear in the Fabric topologyonly when connected on an interface with Security Fabric Connection enabled.

If the VLAN/AP management interface lacksSecurity Fabric Connection:

FortiGate does not treat that network as aFabric connection segment.

CAPWAP discovery from FortiAPs on that VLAN will not result in the AP being onboarded and shown for management.

Therefore the key misconfiguration is:

✔A – Security Fabric is disabled on the VLAN interface used for AP management.

Why the others are not the root cause:

B. Firmware incompatibility– would usually show as a “Managed (upgrade required)” or similar status after discovery, not complete non-detection. The scenario specifically points to a configuration issue, not firmware.

C. VLAN not tagged correctly on uplink– The FortiSwitch uplink to FortiGate is the FortiLink trunk, and the VLAN sub-interface APs is already bound to fortilink, so tagging on the uplink is correct by definition.

D. CAPWAP ports not open– CAPWAP (UDP 5246/5247) is terminated locally on FortiGate and does not depend on any firewall policy; these ports are open on the FortiGate itself by default.

In this design, FortiAuthenticator receivesRADIUS accounting (RSSO) messages, looks up the user in LDAP to get group information, theninjects FSSO logon eventstoward all FortiGate devices.

From the exhibits we know:

FortiAuthenticatoris receiving RADIUS accountingfrom the RADIUS server.

LDAP queries are successful and return group membership.

But FortiGatedoes not receive FSSO logons, so identity-based policies are not applied.

For FortiAuthenticator to create an FSSO logon, the RADIUS accounting record must be correctlyparsed into at least:

Username

Client IP address

These are mapped from the RADIUS attributes in theRADIUS Accounting SSO clientconfiguration (for example, User-Name and Framed-IP-Address). If these are not defined or mapped incorrectly, FortiAuthenticator can see the accounting packet butcannot build a valid FSSO session, so no update is sent to FortiGate.

Thus the most likely root cause is:

✔The RADIUS Username and Client IPv4 attributes are not correctly definedfor that RADIUS Accounting SSO client (optionA).

Other options conflict with the scenario:

B– LDAP is already successfully returning groups.

C– FSSO user group attribute is separate; even without it, FSSO logons would still be created (just without group mapping).

D– The interfaceisreceiving RADIUS accounting, so it is clearly enabled.