This 300-410 practice question tests your understanding of ipsec site-to-site vpn. 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.
In Cisco IOS, what is the default IKEv1 phase 1 authentication method when using a pre-shared key and no explicit authentication is configured?
RSA encrypted nonces
Why wrong: RSA encrypted nonces require certificate configuration and are not default.
Pre-shared key
IOS defaults to pre-shared key authentication when not specified.
Digital signatures (RSA-SIG)
Why wrong: Digital signatures are not the default.
No default; authentication must be explicitly set
Why wrong: Pre-shared key is the default.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Pre-shared key
When no explicit authentication method is configured for IKEv1 phase 1 and a pre-shared key is used, Cisco IOS defaults to 'pre-shared key' authentication. This is because the pre-shared key itself defines the authentication mechanism; the router automatically selects the appropriate authentication method based on the configured key material.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
RSA encrypted nonces
Why it's wrong here
RSA encrypted nonces require certificate configuration and are not default.
Pre-shared key
Why this is correct
IOS defaults to pre-shared key authentication when not specified.
Related concept
Read the scenario before looking for a memorised answer.
Digital signatures (RSA-SIG)
Why it's wrong here
Digital signatures are not the default.
No default; authentication must be explicitly set
Why it's wrong here
Pre-shared key is the default.
Common exam traps
Cisco often tests the misconception that authentication must always be explicitly configured, leading candidates to choose 'No default' when in fact the default is pre-shared key for pre-shared key configurations.
Detailed technical explanation
Under the hood, IKEv1 phase 1 uses the 'authentication' command under the ISAKMP policy to specify the method. If omitted, the router inspects the configured key (e.g., 'crypto isakmp key') and automatically sets the authentication to pre-shared key. In real-world scenarios, forgetting to explicitly set authentication can lead to interoperability issues if the peer expects a different method, but Cisco IOS will still negotiate using the default pre-shared key method.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
IPsec Site-to-Site VPN — study guide chapter
Learn the concepts, then practise the questions
IPsec Site-to-Site VPN practice questions
Targeted practice on this topic area only
All 300-410 questions
2,152 questions across all exam domains
Cisco CCNP ENARSI 300-410 study guide
Full concept coverage aligned to exam objectives
300-410 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise 300-410 questions linked to Layer 3 Technologies.
Practise 300-410 questions linked to EIGRP Troubleshooting.
Practise 300-410 questions linked to OSPF Troubleshooting (v2/v3).
Practise 300-410 questions linked to BGP Troubleshooting.
Practise 300-410 questions linked to Route Redistribution.
Practise 300-410 questions linked to Policy-Based Routing (PBR).
Practise 300-410 questions linked to VRF-Lite.
Practise 300-410 questions linked to Route Maps and Route Filtering.
Practise 300-410 questions linked to Administrative Distance.
Practise 300-410 questions linked to Route Summarization.
Practise 300-410 questions linked to Bidirectional Forwarding Detection (BFD).
Practise 300-410 questions linked to VPN Technologies.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
IPsec Site-to-Site VPN — This question tests IPsec Site-to-Site VPN — Read the scenario before looking for a memorised answer..
The correct answer is: Pre-shared key — When no explicit authentication method is configured for IKEv1 phase 1 and a pre-shared key is used, Cisco IOS defaults to 'pre-shared key' authentication. This is because the pre-shared key itself defines the authentication mechanism; the router automatically selects the appropriate authentication method based on the configured key material.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 →
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.
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.