mediumMultiple ChoiceObjective-mapped
300-410 Practice Question: Runs the following command on Router R1: R1# show…
A network engineer runs the following command on Router R1:
R1# show crypto isakmp sa detail
Codes: C - IKE, M - IKEv2, P - IPsec
C-id Local Remote I-VRF Status Encr Hash Auth DH Lifetime Cap. 1 10.1.1.1 10.1.1.2 ACTIVE aes sha md5 2 86400 2 10.1.1.1 10.1.1.3 ACTIVE aes sha md5 2 86400
Based on this output, what is the problem?
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
✓
The IKE policy uses weak authentication (MD5) and DH group 2.
The output shows IKE phase 1 SAs with encryption aes, hash sha, authentication md5, and DH group 2. The problem is that MD5 is used for authentication, which is considered weak and insecure. Modern DMVPN deployments should use stronger algorithms like SHA-256. Additionally, DH group 2 is weak.
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 IKE policy uses weak authentication (MD5) and DH group 2.
Why this is correct
MD5 and DH group 2 are cryptographically weak.
- ✗
The IKE SAs are not active.
Why it's wrong here
Status is ACTIVE.
- ✗
The IPsec SAs are missing.
Why it's wrong here
This command only shows IKE SAs.
- ✗
The lifetime is too short.
Why it's wrong here
86400 seconds (24 hours) is standard.
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.
Key term
FlexVPN
FlexVPN is a Cisco VPN solution that combines multiple VPN technologies (site-to-site, remote access, and hub-and-spoke) under a single, modular framework based on IKEv2.
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JA
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.