hardMultiple ChoiceObjective-mapped
300-410 Practice Question: A DMVPN network is experiencing spoke-to-spoke…
A DMVPN network is experiencing spoke-to-spoke tunnel failures. R1 (hub) has: event manager applet DMVPN-TRIGGER event syslog pattern "%DMVPN-5-UP" action 1.0 cli command "enable" action 2.0 cli command "clear crypto sa" action 3.0 syslog msg "Cleared crypto SAs". Router R2 (spoke) shows: DMVPN tunnel is up, but IPsec SAs are renegotiating frequently. What is the root cause?
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 EEM applet clears all crypto SAs whenever a DMVPN tunnel comes up, disrupting existing SAs.
The EEM applet triggers on any DMVPN tunnel UP event and clears all crypto security associations (SAs). This forces renegotiation of IPsec SAs for all tunnels, causing temporary loss of spoke-to-spoke connectivity. The correct fix is to clear only specific SAs or avoid clearing them on DMVPN UP events.
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 EEM applet clears all crypto SAs whenever a DMVPN tunnel comes up, disrupting existing SAs.
Why this is correct
Clearing all crypto SAs forces renegotiation, causing spoke-to-spoke failures.
- ✗
The DMVPN tunnel is misconfigured with mismatched IPsec profiles.
Why it's wrong here
No evidence of misconfiguration; the issue is the EEM clear command.
- ✗
The spoke router has an incorrect NHRP mapping.
Why it's wrong here
The tunnel is up, so NHRP is working; the problem is the crypto SA clearing.
- ✗
The hub router has a routing protocol issue preventing spoke-to-spoke routes.
Why it's wrong here
Routing is not mentioned; the issue is the EEM applet.
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.
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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.