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 engine connections active Crypto Engine Connections
ID Type Algorithm Encrypt Decrypt LastSeqNo 1 IPsec ESP-3DES+SHA 0 0 0 2 IPsec ESP-3DES+SHA 0 0 0 3 IPsec ESP-AES+SHA 0 0 0
What does this output indicate?
⚠ Common exam trap
Cisco often tests the misconception that a non-zero number of SAs in 'show crypto engine connections active' automatically means traffic is flowing, when in fact the Encrypt/Decrypt counters must be checked to confirm actual data processing.
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 IPsec SAs are established but no traffic is flowing, possibly due to routing or ACL issues.
The output shows three IPsec Security Associations (SAs) with zero encrypted and zero decrypted packets, and a LastSeqNo of 0. This indicates the SAs are established (the tunnels are up) but no traffic is being processed through them. The most common causes are routing issues preventing traffic from reaching the tunnel interface, or ACLs that do not match the interesting traffic for encryption.
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 actively encrypting and decrypting traffic.
Why it's wrong here
All counters are zero, indicating no traffic.
- ✓
The IPsec SAs are established but no traffic is flowing, possibly due to routing or ACL issues.
Why this is correct
Zero packets suggest the SAs are idle; the issue is likely with traffic matching the crypto ACL or routing.
- ✗
The crypto engine is overloaded and cannot process packets.
Why it's wrong here
There is no indication of overload; the connections are simply idle.
- ✗
The IPsec SAs are using the wrong transform set.
Why it's wrong here
The transform sets are shown, but the issue is lack of traffic, not transform mismatch.
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
About these practice questions
Courseiva writes every 300-410 question from scratch — 1,966 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.