- A
TACACS+
TACACS+ encrypts the entire authentication packet (username, password, etc.) and is commonly used for AAA on network devices (routers/switches).
- B
RADIUS
Why wrong: RADIUS encrypts only the password field; the rest of the packet is sent in clear text. Although RADIUS can be used for device admin, it does not encrypt the entire authentication packet.
- C
LDAP
Why wrong: LDAP is a directory access protocol, not an AAA protocol. It can be used for authentication but does not provide accounting or full packet encryption.
- D
Kerberos
Why wrong: Kerberos is a ticket-based authentication protocol used in Windows domains. It is not typically used for AAA on network devices and does not provide accounting.
Question 435 of 520
N10-009 Network Operations Practice Question
This N10-009 practice question tests your understanding of network operations. 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.
A network administrator needs to implement a solution that allows for centralized management of user authentication, authorization, and accounting for network device access. The solution must support encryption of the entire authentication process. Which protocol should be selected?
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) into distinct processes and encrypts the entire authentication payload, including the username, password, and all other traffic between the client and the server. This full-packet encryption ensures that credentials and session details are protected during transit, meeting the requirement for centralized management with encrypted authentication.
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+
- ✗
RADIUS
Why it's wrong here
RADIUS encrypts only the password field; the rest of the packet is sent in clear text. Although RADIUS can be used for device admin, it does not encrypt the entire authentication packet.
When this WOULD be correct
A network administrator needs a protocol for centralized authentication, authorization, and accounting for network access (e.g., VPN or wireless) that supports encryption of the password only, and the solution must be an open standard.
- ✗
LDAP
Why it's wrong here
LDAP is a directory access protocol, not an AAA protocol. It can be used for authentication but does not provide accounting or full packet encryption.
When this WOULD be correct
A question asks: 'Which protocol is used to centralize user authentication and authorization for accessing directory services, such as verifying user credentials against an Active Directory database?' In that context, LDAP would be the correct answer.
- ✗
Kerberos
Why it's wrong here
Kerberos is a ticket-based authentication protocol used in Windows domains. It is not typically used for AAA on network devices and does not provide accounting.
When this WOULD be correct
A question asks: 'Which protocol provides secure authentication for users accessing services in a Windows domain environment, using a ticket-granting system and supporting mutual authentication?' In that context, Kerberos is the correct answer.
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
TACACS+ encrypts the entire authentication packet (username, password, etc.) and is commonly used for AAA on network devices (routers/switches).
✗RADIUSWrong answer — click to see why▾
Why this is wrong here
RADIUS encrypts only the password in the authentication process, not the entire session, whereas the question requires encryption of the entire authentication process.
★ When this WOULD be the correct answer
A network administrator needs a protocol for centralized authentication, authorization, and accounting for network access (e.g., VPN or wireless) that supports encryption of the password only, and the solution must be an open standard.
Why candidates choose this
Candidates often confuse RADIUS with TACACS+ because both provide AAA services, but they may overlook the encryption scope difference.
✗LDAPWrong answer — click to see why▾
Why this is wrong here
LDAP is primarily a directory access protocol for querying and modifying directory services, not a full AAA protocol. It does not natively support accounting or encrypt the entire authentication process; encryption is typically added via LDAPS, but it lacks the integrated AAA framework required for network device access management.
★ When this WOULD be the correct answer
A question asks: 'Which protocol is used to centralize user authentication and authorization for accessing directory services, such as verifying user credentials against an Active Directory database?' In that context, LDAP would be the correct answer.
Why candidates choose this
Candidates may confuse LDAP's role in authentication (e.g., binding to a directory) with a complete AAA solution, or they might think LDAP with SSL/TLS provides the required encryption and centralized management.
✗KerberosWrong answer — click to see why▾
Why this is wrong here
Kerberos is a ticket-based authentication protocol that does not natively provide centralized accounting for network device access, nor does it encrypt the entire authentication process (only the ticket exchange is encrypted). It is designed for single sign-on in a domain environment, not for AAA of network devices.
★ When this WOULD be the correct answer
A question asks: 'Which protocol provides secure authentication for users accessing services in a Windows domain environment, using a ticket-granting system and supporting mutual authentication?' In that context, Kerberos is the correct answer.
Why candidates choose this
Candidates may confuse Kerberos's strong encryption and authentication capabilities with the AAA requirements, overlooking that it lacks built-in authorization and accounting features for network device management.
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 N10-009 exam often tests the misconception that RADIUS encrypts all traffic because it uses a shared secret, but the trap is that RADIUS only encrypts the password, not the entire packet, whereas TACACS+ encrypts the full authentication payload.
Detailed technical explanation
How to think about this question
TACACS+ uses TCP port 49 and encrypts the entire body of each packet (except the standard header) using a shared secret and MD5-based hashing, ensuring confidentiality for all AAA data. In contrast, RADIUS uses UDP (ports 1812/1813) and only encrypts the password field using a shared secret and MD5, leaving other attributes like username, service type, and accounting data exposed. A real-world scenario where this matters is when auditing network device logins: TACACS+ logs each command executed, while RADIUS typically only logs authentication events, making TACACS+ superior for detailed accounting and security compliance.
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.
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 N10-009 question test?
Network Operations — This question tests Network Operations — 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) into distinct processes and encrypts the entire authentication payload, including the username, password, and all other traffic between the client and the server. This full-packet encryption ensures that credentials and session details are protected during transit, meeting the requirement for centralized management with encrypted authentication.
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
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Last reviewed: Jun 11, 2026
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