SISE Network Access Device Administration Practice Question
What is the primary function of the TACACS+ 'Shared Secret' configured on both the Cisco ISE and the Network Access Device?
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
✓
To authenticate the TACACS+ packet exchange
The shared secret is used to encrypt the TACACS+ packet body and authenticate the connection between the client and 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.
- ✓
To authenticate the TACACS+ packet exchange
Why this is correct
The secret validates the integrity and authenticity of the communication.
- ✗
To assign the device to a specific group
Why it's wrong here
NDGs are used for grouping, not the shared secret.
- ✗
To encrypt the entire packet header
Why it's wrong here
The header is not encrypted; the body is.
- ✗
To enable SSL/TLS encryption for the session
Why it's wrong here
TACACS+ does not use TLS by default; the secret provides MD5/HMAC integrity.
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
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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.