WithAD machine authenticationvia FortiAuthenticator:

When a machine successfully authenticates, FortiAuthenticator records:

Machine account / identity

MAC addressof the device

Associated IP and session info

To handle sleep/hibernation:

FortiAuthenticator keeps acache of authenticated MAC addressesfor a configured timeout.

When the device wakes up and sends traffic again, FortiAuthenticator/FSSO can still treat it as authenticated as long as its MAC is in cache, so access is maintained without forcing a full machine re-auth immediately.

This matches optionD.

A(guest VLAN) is not the standard behavior here.

B(WoL) is unrelated.

C(IP-based) would break as IPs can change; MAC-based caching is what’s used.

From the FortiManager NAC policy:

Category =Device

Match criteria includeMAC addressandOperating System = Linux

Action =Assign VLAN “Students”

From the FortiGate CLI:

diagnose switch-controller switch-info mac-table ...

MAC: 70:88:6b:8c:4a:ce VLAN: 4089 Port: port2

diagnose switch-controller mac-device mac onboarding

VLAN 4089 MAC 70:88:6b:8c:4a:ce

So the device is stuck inVLAN 4089, which is theonboarding VLAN. No NAC policy is matched.

For a NAC policy to match, FortiGate needsdevice-identity information, which comes fromdevice detection on the VLAN / FortiLink interfaceplus theattributes that the policy expects(OS, MAC, etc.).

A. Device detection is not enabled on VLAN 4089.

If device detection is disabled on the interface/VLAN where the endpoint lives, FortiGate cannot learn OS / device info.

Without this, the NAC engine cannot compare against the NAC policy (which relies on OS and other attributes), so the device remains in the onboarding VLAN.✅This is a valid root cause.

B. The device operating system detected by FortiGate is not Linux.

The NAC policy explicitly requiresOperating System = Linux.

If the endpoint is actually Windows/macOS, or the OS fingerprint is still “Unknown”, the policy will never match, and the device stays in onboarding.✅Also a valid reason.

C. Management communication between FortiGate and FortiSwitch is down.

CLI output (switch-info mac-table and mac-device) proves FortiGate is talking to the switch and sees MAC/VLAN/port information.❌Not a valid reason.

D. The MAC address configured on the NAC policy is incorrect.

The exhibits show the MAC in the NAC policy matches the MAC appearing in the MAC table.❌Not the cause here.

When FortiAPs connect to FortiGate overIPsec tunnels, this is treated similarly to WAN/MPLS deployments.

In these scenarios, FortiGate must know that CAPWAP must traverse anon-L2transport.

FortiAP profiles include:

set mpls-connection enable

This setting is required so that:

FortiGate can encapsulate CAPWAP inside the transport tunnel

Remote FortiAPs can establish CAPWAP even when behind routed/IPsec networks

Without this option, the FortiGate detects the AP butcannot bring CAPWAP UP, leaving the AP in “discovered/unauthorized” or “offline” state.

Why others are wrong

A. Static route→ Discovery already succeeds, so routing is not the issue.

C. Reduce MTU→ Sometimes useful for IPsec, but not required for CAPWAP establishment.

D. Firmware upgrade→ Firmware mismatch would show “Managed (upgrade required),” not CAPWAP tunnel failure.

Therefore,set mpls-connection enableis the required fix.

The FortiOS documentation explicitly states that a CSR used for certificate signing must contain accurate and valid fields, especially:

Common Name (CN)

Organization (O)

Country (C)

Public key parameters

According to the FortiGate certificate section:

Incorrect CSR field information can cause the CA to reject the request.

Reasons include:

The CA validates identity and organizational information.

Missing or malformed data invalidates PKI requirements.

The CSR is not corrected automatically by the CA.

Therefore:

✔A is correct.

Options B–D contradict PKI principles:

B is false: CAs do not issue certificates with mismatched identity fields for public trust.

C is false: CSR fields are not only for internal use; they define certificate identity.

D is false: CAs do not auto-correct CSR fields.

Auto TX power control on FortiAP is an RF-optimization feature:

FortiGate (as wireless controller) continuously evaluatesRSSI of associated clientson each FortiAP radio.

The algorithm focuses on theweakest client(the one with the worst signal) and adjusts the AP’s transmit power so that this client’s signal level stays within a configured / target range.

This helps balance coverage and limit co-channel interference: APs don’t transmit at maximum power when clients are close, but will increase power when the weakest client signal drops too low.

Therefore the correct behavior description is:

✔C– AP power is adjusted based on the weakest associated client’s signal.

Why the others are wrong:

AandBtalk about matching nearby APs’ power or forcing everything to –70 dBm, which is not how FortiAP auto TX works.

Dincorrectly states the AP “evaluates its own transmission from the client perspective”; the AP can only infer client-side conditions from theclient’s RSSI at the AP, not the inverse.

From the exhibits and text:

FortiGate →RADIUS→ FortiAuthenticator

FortiAuthenticator →LDAP→ Windows AD

diagnose test authserver radius ... papsucceeds

diagnose test authserver radius ... mschap2fails

This behavior matches a classic limitation documented in FortiOS:

When usingLDAPas the back-end, the RADIUS server must usePAP. CHAP/MS-CHAPv2 arenot supportedwith plain LDAP because the server cannot validate the challenge–response without access to password hashes.

In the Remote LDAP server config on FortiAuthenticator, the option“Windows Active Directory Domain Authentication” is disabled.When this feature isenabled, FortiAuthenticator can talk to AD usingKerberos/NTLMinstead of a simple LDAP bind, whichdoes support MS-CHAPv2for incoming RADIUS authentications.

So to allow MS-CHAPv2 all the way from FortiGate to AD, you must:

Keep FortiGate using RADIUS with MS-CHAPv2 → FortiAuthenticator

EnableWindows Active Directory Domain Authenticationso FortiAuthenticator can properly validate MS-CHAPv2 against AD.

Why the other options are wrong:

A. Change to CHAP– CHAP still cannot be validated over LDAP; docs say LDAP back-ends must usePAP.

C. Manually add users to local DB– That would allow local-DB auth but does not fix MS-CHAPv2 against AD.

D. Use RADIUS attributes on FortiGate– Attributes do not influence the EAP inner method; they don’t fix MS-CHAPv2 failures.

Therefore the configuration change that can realistically fix the MS-CHAPv2 problem isenabling Windows Active Directory Domain Authentication on FortiAuthenticator (B).

FortiGate and FortiSwitchmust share synchronized timewhen operating in FortiLink mode.

Documented reasons in FortiOS:

Accurate time synchronization is required for logs, authentication events, and fabric correlations.

Why it’s critical:

802.1X EAP and RADIUS timestamp validation

NAC policy enforcement timestamps

Certificate validation

Log correlation in Security Fabric / FortiAnalyzer

Incorrect options:

A: Firmware synchronization does NOT require NTP.

B: Switch-to-switch communication does not depend on NTP.

D: Standalone mode is unrelated to time sync.