- A
TACACS+
Correct. TACACS+ encrypts the entire session and supports granular command authorization for device administration.
- B
RADIUS
Why wrong: RADIUS is primarily used for network access authentication (e.g., 802.1X, VPN) and does not provide command-level authorization for device administration.
- C
LDAP
Why wrong: LDAP is used for querying directory services (e.g., user attributes) and does not provide AAA for network devices.
- D
Kerberos
Why wrong: Kerberos provides authentication via tickets but not per-command authorization; it is not typically used for device administration.
Question 42 of 520
N10-009 Network Security Practice Question
This N10-009 practice question tests your understanding of network security. 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.
An organization needs to authenticate network administrators and control which commands each administrator can execute on routers and switches. The solution must support granular per-command authorization and encrypt the entire session. Which protocol is best suited for this requirement?
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+
TACACS+ is the correct choice because it separates authentication, authorization, and accounting (AAA) functions, allowing granular per-command authorization on routers and switches. It encrypts the entire session, including the username, password, and all command traffic, unlike RADIUS which only encrypts the password. This makes TACACS+ ideal for environments requiring strict command-level control and full session encryption.
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+
Why this is correct
Correct. TACACS+ encrypts the entire session and supports granular command authorization for device administration.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
RADIUS
- ✗
LDAP
Why it's wrong here
LDAP is used for querying directory services (e.g., user attributes) and does not provide AAA for network devices.
- ✗
Kerberos
Why it's wrong here
Kerberos provides authentication via tickets but not per-command authorization; it is not typically used for device administration.
When this WOULD be correct
An organization needs to implement single sign-on for users accessing multiple services within a Windows domain, with mutual authentication and ticket-based access control.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓TACACS+Correct answer▾
Why this is correct
Correct. TACACS+ encrypts the entire session and supports granular command authorization for device administration.
✗RADIUSWrong answer — click to see why▾
Why this is wrong here
RADIUS encrypts only the password in the authentication packet, not the entire session, and does not support per-command authorization; it is designed for network access control, not device administration.
★ When this WOULD be the correct answer
When the requirement is to authenticate users for network access (e.g., VPN or 802.1X) and optionally authorize network services, but does not require per-command authorization or full-session encryption.
Why candidates choose this
Candidates often confuse RADIUS with TACACS+ because both are AAA protocols, and they may assume RADIUS also provides command authorization and encryption, not realizing its limitations in device administration contexts.
✗KerberosWrong answer — click to see why▾
Why this is wrong here
Kerberos is designed for authentication and single sign-on in a trusted network, but it does not provide per-command authorization or session encryption for network device administration.
★ When this WOULD be the correct answer
An organization needs to implement single sign-on for users accessing multiple services within a Windows domain, with mutual authentication and ticket-based access control.
Why candidates choose this
Candidates may associate Kerberos with strong authentication and encryption, mistakenly believing it can also handle granular command authorization for network devices.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction that RADIUS is commonly used for network access control (e.g., 802.1X) but fails for device administration because it lacks per-command authorization and full-session encryption, leading candidates to mistakenly choose RADIUS due to its familiarity.
Trap categories for this question
Command / output trap
RADIUS is primarily used for network access authentication (e.g., 802.1X, VPN) and does not provide command-level authorization for device administration.
Detailed technical explanation
How to think about this question
TACACS+ uses TCP port 49 and encrypts the entire payload (authentication, authorization, and accounting packets) using a shared secret key, ensuring no cleartext data is transmitted. For per-command authorization, TACACS+ sends each command to the AAA server, which checks against a configured privilege level or command set (e.g., via 'authorization commands 15' in Cisco IOS), allowing or denying execution in real time. In contrast, RADIUS uses UDP (ports 1812/1813) and only encrypts the password field, making it unsuitable for environments where command-level auditing and encryption are required.
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.
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.
What to study next
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FAQ
Questions learners often ask
What does this N10-009 question test?
Network Security — This question tests Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: TACACS+ — TACACS+ is the correct choice because it separates authentication, authorization, and accounting (AAA) functions, allowing granular per-command authorization on routers and switches. It encrypts the entire session, including the username, password, and all command traffic, unlike RADIUS which only encrypts the password. This makes TACACS+ ideal for environments requiring strict command-level control and full session encryption.
What should I do if I get this N10-009 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 30, 2026
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