The answer is that the RADIUS authentication port is 1645 and the accounting port is 1646, as explicitly configured. This is correct because while the IANA-standard ports for RADIUS are UDP 1812 for authentication and 1813 for accounting, many legacy devices and older Cisco IOS versions historically used ports 1645 and 1646 before the standard was formalized. The configuration shown overrides the defaults with these legacy ports, making them valid but non-standard. On the ENCOR 350-401 exam, this tests your understanding of RADIUS port configuration and the common trap that the default ports are always 1812/1813—but the configuration explicitly sets them, so you must read the running config carefully. A strong memory tip is to think of the older ports as "16-45" and "16-46" predating the "18-12" and "18-13" standard, or simply remember that 1645 is for authentication and 1646 is for accounting, just one digit apart.
350-401 AAA, RADIUS, and TACACS+ Practice Question
This 350-401 practice question tests your understanding of aaa, radius, and tacacs+. 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.
Given this configuration:
aaa new-model
aaa authentication login default group radius
aaa authorization exec default group radius
aaa accounting exec default start-stop group radius
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The RADIUS authentication port is 1645 and accounting port is 1646.
RADIUS traditionally uses UDP port 1812 for authentication and 1813 for accounting, but older implementations use 1645 and 1646. The configuration explicitly sets these ports, which is valid but non-standard.
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.
✓
The RADIUS authentication port is 1645 and accounting port is 1646.
Why this is correct
Correct. The 'auth-port' and 'acct-port' keywords explicitly set these ports.
Related concept
Authentication checks who the user is.
✗
The RADIUS authentication port is 1812 and accounting port is 1813.
Why it's wrong here
Incorrect. The configuration overrides the default ports with 1645 and 1646.
✗
The RADIUS authentication port is 1646 and accounting port is 1645.
Why it's wrong here
Incorrect. The ports are swapped; auth-port is 1645, acct-port is 1646.
✗
The RADIUS ports are not configurable; this command will be rejected.
Why it's wrong here
Incorrect. The 'auth-port' and 'acct-port' keywords are valid and configurable.
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.
Trap categories for this question
Keyword trap
Incorrect. The 'auth-port' and 'acct-port' keywords are valid and configurable.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
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: The RADIUS authentication port is 1645 and accounting port is 1646. — RADIUS traditionally uses UDP port 1812 for authentication and 1813 for accounting, but older implementations use 1645 and 1646. The configuration explicitly sets these ports, which is valid but non-standard.
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 →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 350-401 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 350-401 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.