mediumMultiple Choice
300-410 Practice Question: Runs the following command to troubleshoot IPsec…
A network engineer runs the following command to troubleshoot IPsec on a DMVPN tunnel:
R1# debug crypto isakmp
ISAKMP: received peer 192.168.1.2, port 500, local 192.168.1.1 ISAKMP: SA created, initiating IKE Main Mode ISAKMP: sent MM_SA proposal to 192.168.1.2 ISAKMP: received MM_SA response from 192.168.1.2 ISAKMP: Main Mode complete, starting Quick Mode ISAKMP: sent QM_SA request to 192.168.1.2 ISAKMP: received QM_SA response from 192.168.1.2 ISAKMP: Quick Mode done, IPsec SA established
What does this output indicate?
⚠ Common exam trap
The trap is that candidates might misinterpret the debug output as indicating a failure because it shows messages, but the key is to look for the final 'IPsec SA established' line, which confirms success.
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
✓
IKE negotiation succeeded and an IPsec SA is now active.
The debug output shows that IKE Main Mode completed successfully, Quick Mode completed, and an IPsec SA was established. This indicates that the IKE negotiation succeeded and the tunnel is active.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
IKE negotiation failed; no IPsec SA was established.
Why it's wrong here
The log shows Main Mode completing and Quick Mode finishing with the IPsec SA established, so negotiation succeeded. A failure would appear as no proposal chosen or a timeout during MM_SA or QM_SA exchange; this output confirms the tunnel came up.
- ✓
IKE negotiation succeeded and an IPsec SA is now active.
Why this is correct
The debug trace shows IKE Main Mode completing, then Quick Mode exchanging proposals and completing, with the final line confirming the IPsec SA is established. Phase 1 and Phase 2 negotiation both succeeded between the peers.
- ✗
The peer 192.168.1.2 is not responding to IKE requests.
Why it's wrong here
The log shows bidirectional IKE exchange completing: MM_SA response received, Quick Mode done, and IPsec SA established, so the peer clearly answered. It tempts engineers because silence after sending MM_SA is the classic symptom of an unreachable or misconfigured peer, but here both MM and QM responses arrived.
- ✗
IKE is using Aggressive Mode instead of Main Mode.
Why it's wrong here
The log explicitly states "initiating IKE Main Mode" and "Main Mode complete", so Aggressive Mode was never negotiated. Aggressive Mode is tempting because it reduces IKE exchanges to three messages for remote-access peers with dynamic IP addresses, but this DMVPN tunnel used six-message Main Mode with identity protection.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
Go deeper
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Same concept, more angles
1 more way this is tested on 300-410
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network engineer runs the following command on Router R1: R1# show crypto isakmp sa dst src state conn-id slot status 10.1.1.2 10.1.1.1 MM_ACTIVE 1 0 ACTIVE 10.1.1.3 10.1.1.1 MM_ACTIVE 2 0 ACTIVE Based on this output, which statement is correct?
medium- ✓ A.IKE phase 1 is complete for both peers.
- B.IKE phase 2 is complete for both peers.
- C.The IPsec tunnels are established.
- D.The peers are not responding.
Why A: The show crypto isakmp sa command shows IKE phase 1 security associations. The state MM_ACTIVE indicates that IKE phase 1 is complete and active. The output shows two active SAs with the local router (10.1.1.1) and two remote peers (10.1.1.2 and 10.1.1.3).
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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.