The root cause is the EEM applet clearing all crypto SAs whenever a DMVPN tunnel comes up, which disrupts existing spoke-to-spoke IPsec security associations. This happens because the applet triggers on the syslog pattern "%DMVPN-5-UP" and executes "clear crypto sa" without filtering, forcing all tunnels to renegotiate their SAs simultaneously. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your understanding of how EEM applets interact with DMVPN tunnel failures and the importance of granular SA management—a common trap is assuming any "clear crypto" command is harmless during troubleshooting. The key insight is that the hub’s applet does not differentiate between new and existing tunnels, causing frequent renegotiation on the spoke. For the exam, remember: when you see an EEM applet tied to a DMVPN syslog event with a blanket "clear crypto sa," think "one size fits all—and fails all." Memory tip: "UP clears all, then all fall down."
300-410 Embedded Event Manager (EEM) Practice Question
This 300-410 practice question tests your understanding of embedded event manager (eem). Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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 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.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Related concept
Static NAT maps one inside address to one outside address.
✗
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.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Trap categories for this question
Command / output trap
No evidence of misconfiguration; the issue is the EEM clear command.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 300-410 NAT questions on configuration and troubleshooting.
Embedded Event Manager (EEM) — This question tests Embedded Event Manager (EEM) — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this 300-410 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 300-410 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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