Question 143 of 2,152

Embedded Event Manager (EEM) →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the EEM applet fails to trigger because a network type mismatch between broadcast and point-to-point prevents the routers from ever reaching the 2WAY state, so no OSPF-5-ADJCHG syslog is generated. This occurs because the Hello packets are interpreted differently—broadcast expects a DR/BDR election and uses a 40-second dead interval, while point-to-point skips the election and uses a 120-second dead interval—causing the neighbor relationship to stall in INIT or EXSTART. On the Cisco CCNP ENARSI 300-410 exam, this tests your understanding that the ADJCHG syslog only fires when there is a state change from FULL to DOWN (or vice versa); if the adjacency never forms, no such message appears. A common trap is assuming any OSPF failure triggers ADJCHG, but mismatched network types often produce only OSPF-4-ERRRCV or nothing at all. Memory tip: “No 2WAY, no ADJCHG—mismatched types kill the handshake before the log can sing.”

300-410 Embedded Event Manager (EEM) Practice Question

This 300-410 practice question tests your understanding of embedded event manager (eem). The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 network engineer configures an EEM applet to monitor OSPF network type mismatches using the event syslog pattern 'OSPF-5-ADJCHG'. The applet is supposed to send a notification when an adjacency fails. Two routers are connected with an OSPF network type mismatch (one is broadcast, the other is point-to-point). The adjacency fails, but the EEM applet does not trigger. Which is the most likely explanation?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice

Review the full OSPF breakdown →

A
A network type mismatch prevents the routers from reaching the 2WAY state, so no OSPF-5-ADJCHG syslog is generated.
Correct. The adjacency fails early, and the syslog for state change is not generated because FULL was never reached.
B
The EEM applet must use 'event ospf' to capture OSPF network type mismatches.
Why wrong: EEM does not have a native OSPF event trigger for network type mismatches.
C
The network type mismatch generates a syslog with pattern 'OSPF-4-ERRRCV', but the EEM applet is looking for 'OSPF-5-ADJCHG'.
Why wrong: This is partially true, but the key point is that no ADJCHG is generated because FULL is never reached.
D
The OSPF process must be restarted for the EEM applet to detect the mismatch.
Why wrong: Restarting OSPF does not change the syslog generation behavior.

Full breakdown with real-world context →

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

✓

A network type mismatch prevents the routers from reaching the 2WAY state, so no OSPF-5-ADJCHG syslog is generated.

When OSPF network types mismatch, the adjacency may fail during the database exchange process, but the syslog message generated is often 'OSPF-4-ERRRCV' or 'OSPF-5-ADJCHG' depending on the specific failure. However, if the mismatch is between broadcast and point-to-point, the routers may not even form a neighbor relationship because they interpret Hello packets differently. In some IOS versions, the syslog message is not generated at all because the routers never reach the 2WAY state. The EEM applet relies on the 'OSPF-5-ADJCHG' pattern, which is only generated when there is a state change from FULL to DOWN or vice versa. If the adjacency never progresses beyond INIT, no ADJCHG message is produced.

Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
A network type mismatch prevents the routers from reaching the 2WAY state, so no OSPF-5-ADJCHG syslog is generated.
Why this is correct
Correct. The adjacency fails early, and the syslog for state change is not generated because FULL was never reached.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
OSPF neighbours must agree on key parameters.
✗
The EEM applet must use 'event ospf' to capture OSPF network type mismatches.
Why it's wrong here
EEM does not have a native OSPF event trigger for network type mismatches.
✗
The network type mismatch generates a syslog with pattern 'OSPF-4-ERRRCV', but the EEM applet is looking for 'OSPF-5-ADJCHG'.
Why it's wrong here
This is partially true, but the key point is that no ADJCHG is generated because FULL is never reached.
✗
The OSPF process must be restarted for the EEM applet to detect the mismatch.
Why it's wrong here
Restarting OSPF does not change the syslog generation behavior.

Common exam traps

Common exam trap: OSPF can fail even when IP connectivity looks correct

OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.

Detailed technical explanation

How to think about this question

OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.

KKey Concepts to Remember

OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.

TExam Day Tips

Check area mismatch first when OSPF adjacency fails.
Review passive interfaces when a network is advertised but no neighbour forms.
Use show ip ospf neighbor and show ip route clues carefully.

Key takeaway

OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.

Real-world example

How this comes up in practice

A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.

What to study next

Got this wrong? Here's your next step.

Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 300-410 OSPF questions on adjacency and route selection.

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FAQ

Questions learners often ask

What does this 300-410 question test?

Embedded Event Manager (EEM) — This question tests Embedded Event Manager (EEM) — OSPF neighbours must agree on key parameters..

What is the correct answer to this question?

The correct answer is: A network type mismatch prevents the routers from reaching the 2WAY state, so no OSPF-5-ADJCHG syslog is generated. — When OSPF network types mismatch, the adjacency may fail during the database exchange process, but the syslog message generated is often 'OSPF-4-ERRRCV' or 'OSPF-5-ADJCHG' depending on the specific failure. However, if the mismatch is between broadcast and point-to-point, the routers may not even form a neighbor relationship because they interpret Hello packets differently. In some IOS versions, the syslog message is not generated at all because the routers never reach the 2WAY state. The EEM applet relies on the 'OSPF-5-ADJCHG' pattern, which is only generated when there is a state change from FULL to DOWN or vice versa. If the adjacency never progresses beyond INIT, no ADJCHG message is produced.

What should I do if I get this 300-410 question wrong?

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

OSPF neighbours must agree on key parameters.

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