The answer is that the IKEv2 negotiation will fail because no common proposal exists between the two routers. This occurs because IKEv2 requires an exact match on all parameters—encryption, hash, and Diffie-Hellman group—within at least one configured proposal; the local router offers AES-256 with SHA-256, while the remote router only supports AES-128 with SHA-1, leaving no overlapping transform set. On the Cisco SCOR 350-701 exam, this scenario tests your understanding of IKEv2’s strict proposal matching, often appearing as a trap where candidates assume automatic fallback or parameter mixing, which IKEv2 does not perform. A common memory tip is to remember that IKEv2 is “all or nothing”—if even one parameter differs, the negotiation fails without negotiation or downgrade.
350-701 Network Security Practice Question
This 350-701 practice question tests your understanding of network security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 engineer is trying to establish a site-to-site IPsec VPN between two Cisco routers. The IKEv2 proposal uses AES-256 encryption and SHA-256 hash. On the remote router, the configuration shows only AES-128 and SHA-1. What will happen during IKEv2 negotiation?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The IKEv2 negotiation will fail because no common proposal exists.
IKEv2 negotiation requires that both peers have at least one matching proposal (encryption, hash, DH group, etc.) in their configured transform sets. Since the local router offers AES-256/SHA-256 and the remote router only offers AES-128/SHA-1, there is no common proposal. IKEv2 does not perform automatic fallback or mixing of parameters; it simply fails if no match is found.
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.
✗
The router with stronger proposal will override the other.
Why it's wrong here
No overriding; they must match exactly on an offered proposal.
✓
The IKEv2 negotiation will fail because no common proposal exists.
Why this is correct
Both sides must have at least one matching proposal for IKEv2 to establish.
Related concept
Read the scenario before looking for a memorised answer.
✗
The routers will automatically fall back to IKEv1.
Why it's wrong here
IKEv2 and IKEv1 are different protocols; no automatic fallback.
✗
The routers will negotiate and use AES-128 with SHA-256.
Why it's wrong here
IKEv2 picks a match from each side's proposals; they must share a common proposal.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that IKEv2 will automatically negotiate a 'best common' set of parameters or fall back to IKEv1, when in fact it requires an exact match on the entire proposal and has no backward compatibility with IKEv1.
Detailed technical explanation
How to think about this question
IKEv2 uses a proposal exchange where each side sends a list of supported transform sets; the responder selects the first matching proposal from the initiator's list. If no match exists, the responder sends a 'NO_PROPOSAL_CHOSEN' notification and the session terminates. In real-world deployments, this mismatch often occurs when one router is updated with stronger algorithms while the other remains on legacy settings, requiring careful coordination of crypto maps or IKE profiles.
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 practitioner preparing for the 350-701 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
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: The IKEv2 negotiation will fail because no common proposal exists. — IKEv2 negotiation requires that both peers have at least one matching proposal (encryption, hash, DH group, etc.) in their configured transform sets. Since the local router offers AES-256/SHA-256 and the remote router only offers AES-128/SHA-1, there is no common proposal. IKEv2 does not perform automatic fallback or mixing of parameters; it simply fails if no match is found.
What should I do if I get this 350-701 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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Question Discussion
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