- A
TACACS+ encrypts the entire packet body, including the username and password, using a shared secret.
TACACS+ encrypts the entire payload (except the header) using the shared secret, providing full confidentiality for authentication data.
- B
RADIUS encrypts the entire packet payload, including the username and password, using a shared secret.
Why wrong: RADIUS encrypts only the password field in the Access-Request packet; other fields like username are sent in cleartext.
- C
TACACS+ uses UDP port 49 by default for communication.
Why wrong: TACACS+ uses TCP port 49 by default, not UDP; RADIUS uses UDP ports 1812 (authentication) and 1813 (accounting).
- D
RADIUS combines authentication and authorization in a single packet, while TACACS+ separates them.
RADIUS bundles authentication and authorization together in the Access-Accept packet, whereas TACACS+ uses separate packets for each AAA function.
- E
Both TACACS+ and RADIUS support per-command authorization for exec sessions.
Why wrong: Only TACACS+ supports per-command authorization; RADIUS does not natively support command-level authorization in Cisco IOS.
Quick Answer
The correct answer is that RADIUS combines authentication and authorization in a single packet, while TACACS+ separates them into distinct processes. This distinction stems from how each protocol handles the AAA framework: RADIUS, originally developed by Livingston Enterprises for network access, bundles authentication and authorization together in one packet exchange, meaning a user is either fully authenticated and authorized or denied entirely, whereas TACACS+, a Cisco-proprietary protocol, uses separate TCP-based sessions for authentication, authorization, and accounting, allowing granular control over each step. On the Cisco CCNP ENARSI 300-410 exam, this concept tests your understanding of AAA protocol behavior in Cisco IOS, often appearing in multiple-choice questions that ask you to identify true statements about TACACS+ and RADIUS differences. A common trap is assuming both protocols encrypt the same way—remember that TACACS+ encrypts the entire packet body, including username and password, while RADIUS only encrypts the password field. For a quick memory tip, think of TACACS+ as "Three Separate Services" (AAA separated) and RADIUS as "One Combined Ride" (auth and authz together).
300-410 Device Access Control Practice Question
This 300-410 practice question tests your understanding of device access control. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 TWO statements about TACACS+ and RADIUS are true? (Choose TWO.)
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
TACACS+ encrypts the entire packet body, including the username and password, using a shared secret.
A is correct because TACACS+ encrypts the entire packet body, including the username and password, using a shared secret. This provides confidentiality for all authentication and authorization data, unlike RADIUS which only encrypts the password field.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
TACACS+ encrypts the entire packet body, including the username and password, using a shared secret.
Why this is correct
TACACS+ encrypts the entire payload (except the header) using the shared secret, providing full confidentiality for authentication data.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
RADIUS encrypts the entire packet payload, including the username and password, using a shared secret.
Why it's wrong here
RADIUS encrypts only the password field in the Access-Request packet; other fields like username are sent in cleartext.
- ✗
TACACS+ uses UDP port 49 by default for communication.
- ✓
RADIUS combines authentication and authorization in a single packet, while TACACS+ separates them.
- ✗
Both TACACS+ and RADIUS support per-command authorization for exec sessions.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that RADIUS encrypts the entire payload like TACACS+, or that TACACS+ uses UDP, leading candidates to incorrectly select option B or C.
Trap categories for this question
Command / output trap
Only TACACS+ supports per-command authorization; RADIUS does not natively support command-level authorization in Cisco IOS.
Detailed technical explanation
How to think about this question
TACACS+ separates authentication, authorization, and accounting (AAA) into distinct processes, allowing granular control such as per-command authorization via the 'aaa authorization commands' feature. RADIUS combines authentication and authorization in a single Access-Accept packet, making it less flexible for detailed command-level policies. In real-world deployments, TACACS+ is preferred for device administration (e.g., Cisco IOS exec sessions) while RADIUS is commonly used for network access (e.g., VPN or wireless).
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this 300-410 question test?
Device Access Control — This question tests Device Access Control — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: TACACS+ encrypts the entire packet body, including the username and password, using a shared secret. — A is correct because TACACS+ encrypts the entire packet body, including the username and password, using a shared secret. This provides confidentiality for all authentication and authorization data, unlike RADIUS which only encrypts the password field.
What should I do if I get this 300-410 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This 300-410 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 300-410 exam.
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