350-401 Question 279
Select 3A network administrator is troubleshooting a wireless network where clients are unable to connect to a WPA2-Enterprise secured SSID. Upon inspecting the packet captures, the administrator notices that the 4-way handshake fails after the client receives the Group Temporal Key (GTK). Which of the following could be a possible cause of the issue?
- A
The client does not support the encryption cipher specified by the access point.
- B
The RADIUS server is not responding to the authentication requests.
- C
The client device has an incorrect PSK configured.
- D
The access point's Group Key Rotation Interval is set too low.
- E
The client is failing to send the Message 4 of the handshake back to the access point.
Show answer and explanation
Correct answers: A, D, E
Explanation
The 4-way handshake in WPA2 ensures mutual authentication and key exchange between the client and the access point. If the client doesn't support the encryption cipher, it won't be able to process the keys, leading to a failure. Similarly, if the Group Key Rotation Interval is too low, the client may not process the GTK correctly. Finally, if the client fails to send Message 4, the handshake cannot be completed. On the other hand, issues like RADIUS server failures or incorrect PSKs pertain to earlier stages in the authentication process and do not directly cause a 4-way handshake failure.
- A. Correct.
The encryption cipher mismatch can cause a failure during the 4-way handshake, as the client cannot process the keys provided by the access point.
- B. Incorrect.
While the RADIUS server handles the authentication phase, a failure in the 4-way handshake specifically occurs after successful authentication, making this not a likely cause.
- C. Incorrect.
An incorrect PSK would cause the connection to fail before the handshake process begins, as it is specific to WPA2-Personal, not WPA2-Enterprise.
- D. Correct.
If the Group Key Rotation Interval is set too low, the client may fail to process the GTK in time, leading to a failure during the handshake.
- E. Correct.
Failure to send Message 4 back to the access point would result in an incomplete 4-way handshake, causing the connection to fail.