SISE BYOD Practice Question
Which of the following is a common reason for a 'Certificate Mismatch' error during EAP-TLS?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The client does not trust the Root CA that signed the server certificate
This occurs when the Root CA certificate on the client does not match the CA that signed the certificate provided by the ISE server.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The ISE node time is out of sync
Why it's wrong here
Time sync issues usually cause 'Certificate Expired' or 'Not Yet Valid' errors.
- ✓
The client does not trust the Root CA that signed the server certificate
Why this is correct
Trust is the foundational requirement for successful EAP-TLS handshakes.
- ✗
The device is not in the correct VLAN
Why it's wrong here
VLAN assignment happens after auth; it does not cause certificate errors.
- ✗
The SSID is not configured for EAP-TLS
Why it's wrong here
This would lead to an authentication failure, not a certificate mismatch.
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
About these practice questions
This SISE question is part of Courseiva's 322-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Cisco exam blueprint
This SISE practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SISE exam.