easyMultiple ChoiceObjective-mapped
300-410 Practice Question: Runs the following command to troubleshoot an…
A network engineer runs the following command to troubleshoot an IPsec Site-to-Site VPN issue:
R1# show crypto isakmp sa detail
IPv4 Crypto ISAKMP SA C-id Local Remote I-VRF Status Encr Hash Auth DH Lifetime Cap. 1001 192.168.1.1 192.168.2.2 ACTIVE des sha pre 2 23:59:21 1002 192.168.1.1 192.168.2.2 ACTIVE 3des sha pre 2 23:58:15
IPv6 Crypto ISAKMP SA
What does this output indicate?
⚠ Common exam trap
Cisco often tests the misconception that multiple active ISAKMP SAs between the same peers are normal or provide redundancy, when in fact they indicate a configuration error that can break the VPN tunnel.
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
✓
There are two active ISAKMP SAs between the peers, which suggests a configuration error such as multiple ISAKMP policies or aggressive mode issues.
The output shows two active ISAKMP SAs between the same peers (192.168.1.1 and 192.168.2.2) with different encryption algorithms (DES and 3DES). Under normal operation, only one ISAKMP SA should exist per peer pair. Having multiple SAs indicates a configuration error, such as multiple ISAKMP policies that both match, or aggressive mode causing duplicate SAs. This is not a sign of redundancy; ISAKMP SAs are not redundant by design.
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 IPsec VPN is functioning correctly with two redundant ISAKMP SAs.
Why it's wrong here
Multiple ISAKMP SAs between same peers is not normal and indicates a problem.
- ✓
There are two active ISAKMP SAs between the peers, which suggests a configuration error such as multiple ISAKMP policies or aggressive mode issues.
Why this is correct
Having two SAs is abnormal; it often results from misconfigured policies or aggressive mode causing duplicate SAs.
- ✗
The ISAKMP SA is using DES encryption, which is weak and should be upgraded.
Why it's wrong here
While DES is weak, the primary issue is the duplicate SAs, not the encryption strength.
- ✗
The ISAKMP SA lifetime is about 24 hours, which is the default.
Why it's wrong here
The lifetime is default, but the main issue is the duplicate SAs.
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
Related to this question
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
Key term
MPLS Layer 3 VPN
A technology that uses Multiprotocol Label Switching to create secure, scalable virtual private networks that connect multiple sites at the network layer, where the service provider manages routing between customer sites.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.