- A
RADIUS with EAP-TLS
Why wrong: EAP-TLS provides strong authentication encryption, but RADIUS still only encrypts the password in the packet payload. It does not encrypt the entire packet nor provide per-command authorization logging.
- B
TACACS+
Correct. TACACS+ encrypts the entire authentication packet and separates AAA functions, enabling detailed command-level authorization logging.
- C
LDAP over SSL
Why wrong: LDAP is a directory access protocol, not a AAA protocol. It does not inherently provide accounting or per-command authorization for network devices.
- D
Kerberos
Why wrong: Kerberos is an authentication protocol used primarily for domain environments (e.g., Windows Active Directory). It does not typically handle authorization for network device commands or accounting.
N10-009 Network Security Practice Question
This N10-009 practice question tests your understanding of network security. 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.
An organization uses a AAA server for network device authentication. The security team requires that all authentication traffic be fully encrypted and that authorization commands be logged per user. 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 best choice because it encrypts the entire authentication packet (including username, password, and all other fields) and supports per-user command authorization logging. This meets the requirement for fully encrypted authentication traffic and detailed audit trails for each user's commands.
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.
- ✗
RADIUS with EAP-TLS
Why it's wrong here
EAP-TLS provides strong authentication encryption, but RADIUS still only encrypts the password in the packet payload. It does not encrypt the entire packet nor provide per-command authorization logging.
When this WOULD be correct
A question that asks for a protocol that provides strong authentication encryption for wireless or remote access, where per-command authorization logging is not required, and the focus is on secure authentication using certificates.
- ✓
TACACS+
- ✗
LDAP over SSL
Why it's wrong here
LDAP is a directory access protocol, not a AAA protocol. It does not inherently provide accounting or per-command authorization for network devices.
When this WOULD be correct
An organization needs to centralize user authentication and authorization for directory services (e.g., Active Directory) with encrypted transmission. The question would specify 'user authentication for accessing network resources' and 'directory service integration' without requiring command-level logging.
- ✗
Kerberos
Why it's wrong here
Kerberos is an authentication protocol used primarily for domain environments (e.g., Windows Active Directory). It does not typically handle authorization for network device commands or accounting.
When this WOULD be correct
An exam question that asks for a protocol providing mutual authentication and single sign-on in a Windows domain environment, without requiring per-command authorization logging.
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 authentication packet and separates AAA functions, enabling detailed command-level authorization logging.
✗RADIUS with EAP-TLSWrong answer — click to see why▾
Why this is wrong here
RADIUS with EAP-TLS encrypts only the authentication traffic (EAP within RADIUS), but the RADIUS protocol itself does not encrypt the entire session, and it does not log authorization commands per user. TACACS+ is required for full encryption and per-command logging.
★ When this WOULD be the correct answer
A question that asks for a protocol that provides strong authentication encryption for wireless or remote access, where per-command authorization logging is not required, and the focus is on secure authentication using certificates.
Why candidates choose this
Candidates may know that EAP-TLS provides strong encryption for authentication and mistakenly assume that RADIUS with EAP-TLS meets all requirements, overlooking TACACS+'s superior command logging and full session encryption.
✗LDAP over SSLWrong answer — click to see why▾
Why this is wrong here
LDAP over SSL encrypts authentication traffic but does not provide per-user command authorization logging, which is a key requirement for this question. TACACS+ is specifically designed for device administration with full encryption and command logging.
★ When this WOULD be the correct answer
An organization needs to centralize user authentication and authorization for directory services (e.g., Active Directory) with encrypted transmission. The question would specify 'user authentication for accessing network resources' and 'directory service integration' without requiring command-level logging.
Why candidates choose this
Candidates may confuse LDAP over SSL with a protocol that handles both authentication and authorization for network devices, or they may think encryption alone satisfies the requirement without considering the need for per-user command logging.
✗KerberosWrong answer — click to see why▾
Why this is wrong here
Kerberos does not encrypt authorization commands or log per-user commands; it is designed for single sign-on and mutual authentication, not for detailed command accounting on network devices.
★ When this WOULD be the correct answer
An exam question that asks for a protocol providing mutual authentication and single sign-on in a Windows domain environment, without requiring per-command authorization logging.
Why candidates choose this
Candidates may confuse Kerberos's strong encryption and authentication capabilities with the need for command-level authorization and logging, assuming it covers all AAA functions.
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
The trap here is that candidates often confuse RADIUS's partial encryption (password only) with full encryption, or assume LDAP over SSL can handle device AAA, but TACACS+ is the only protocol that fully encrypts all traffic and logs per-user commands for network device administration.
Trap categories for this question
Command / output trap
EAP-TLS provides strong authentication encryption, but RADIUS still only encrypts the password in the packet payload. It does not encrypt the entire packet nor provide per-command authorization logging.
Detailed technical explanation
How to think about this question
TACACS+ uses TCP port 49 and separates authentication, authorization, and accounting into distinct processes, allowing granular control. The entire TACACS+ payload is encrypted using a shared secret and MD5-based encryption, unlike RADIUS which only encrypts the password. In practice, TACACS+ is preferred for device administration (e.g., Cisco IOS) because it can log every command executed by a user, enabling forensic audits and compliance with standards like PCI DSS.
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
Got this wrong? Here's your next step.
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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 best choice because it encrypts the entire authentication packet (including username, password, and all other fields) and supports per-user command authorization logging. This meets the requirement for fully encrypted authentication traffic and detailed audit trails for each user's commands.
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.
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 →
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Last reviewed: Jun 11, 2026
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