SDSI Secure Infrastructure Design Practice Question
Which Cisco feature is used to prevent unauthorized devices from connecting to the wired network by enforcing identity-based access control at the access switch port?
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
✓
802.1X
IEEE 802.1X is the standard for port-based network access control.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
MAC Authentication Bypass
Why it's wrong here
MAB is a fallback mechanism, not the primary method for secure 802.1X environments.
- ✗
Port Security
Why it's wrong here
Port security limits MAC addresses but is not identity-aware.
- ✗
DHCP Snooping
Why it's wrong here
DHCP snooping prevents rogue DHCP servers, not unauthorized device access.
- ✓
802.1X
Why this is correct
802.1X provides authentication via RADIUS/ISE before granting access.
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 SDSI question is part of Courseiva's 298-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 SDSI 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 SDSI exam.