The answer is that RADIUS encrypts only the password, while TACACS+ encrypts the entire packet body. This difference stems from their underlying architectures: RADIUS, defined by RFC 2865, combines authentication and authorization and only obscures the password field in the access-request packet, leaving attributes like username and service type in cleartext. TACACS+, a Cisco-proprietary protocol, separates authentication, authorization, and accounting (AAA) and encrypts the entire packet body except the header, providing full confidentiality for all exchanged data. On the ENCOR 350-401 exam, this distinction often appears in a multiple-choice question testing your understanding of AAA protocol security features, with a common trap being the assumption that RADIUS encrypts all traffic. A reliable memory tip is to think of RADIUS as “RADIUS only hides the password” and TACACS+ as “TACACS+ TOTALLY encrypts the body.”
CCNP AAA, RADIUS, and TACACS+ Practice Question
This 350-401 practice question tests your understanding of aaa, radius, and tacacs+. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which statement correctly describes the difference between RADIUS and TACACS+?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
RADIUS encrypts only the password; TACACS+ encrypts the entire packet body.
RADIUS encrypts only the password in the access-request packet, while TACACS+ encrypts the entire packet body (excluding the header). This is a key security difference.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
RADIUS encrypts the entire packet; TACACS+ encrypts only the password.
Why it's wrong here
Incorrect. The opposite is true: TACACS+ encrypts the entire packet body, RADIUS only the password.
✓
RADIUS encrypts only the password; TACACS+ encrypts the entire packet body.
Why this is correct
Correct. RADIUS encrypts only the password attribute, while TACACS+ encrypts the entire payload.
Related concept
Authentication checks who the user is.
✗
Both protocols encrypt the entire packet.
Why it's wrong here
Incorrect. Only TACACS+ encrypts the entire packet body; RADIUS encrypts only the password.
✗
Neither protocol encrypts any part of the packet.
Why it's wrong here
Incorrect. Both protocols provide encryption; RADIUS encrypts the password, TACACS+ encrypts the payload.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-401 questions on access control and AAA configuration.
AAA, RADIUS, and TACACS+ — This question tests AAA, RADIUS, and TACACS+ — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: RADIUS encrypts only the password; TACACS+ encrypts the entire packet body. — RADIUS encrypts only the password in the access-request packet, while TACACS+ encrypts the entire packet body (excluding the header). This is a key security difference.
What should I do if I get this 350-401 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-401 questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Drag and drop each protocol on the left to its matching characteristic on the right.
medium
✓ P1.RADIUS: Uses UDP transport
✓ P2.TACACS+: Uses TCP transport
✓ P3.RADIUS: Encrypts only the password in the packet
✓ P4.TACACS+: Encrypts the entire packet payload
✓ P5.RADIUS: Combines authentication and authorization into one process
Why P1: RADIUS uses UDP, encrypts only the password, and combines authentication and authorization. TACACS+ uses TCP, encrypts the entire packet, and separates authentication, authorization, and accounting.
Variation 2. Drag and drop each protocol on the left to its matching characteristic on the right.
medium
✓ P1.RADIUS: Uses UDP transport
✓ P2.TACACS+: Encrypts entire packet payload
✓ P3.RADIUS: Combines authentication and authorization in one packet
✓ P4.TACACS+: Separates authentication, authorization, and accounting into separate packets
✓ P5.RADIUS: Typically used for network access (e.g., 802.1X)
Why P1: RADIUS uses UDP and encrypts only the password; TACACS+ uses TCP and encrypts the entire packet. RADIUS combines authentication and authorization; TACACS+ separates them. RADIUS is commonly used for network access; TACACS+ for device administration.
Last reviewed: Jun 18, 2026
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