hardMultiple Select
350-401 Practice Question: Which three statements about SNMP trap and inform…
Which three statements about SNMP trap and inform operations are true? (Choose three.)
⚠ Common exam trap
350-401 often tests the reliability inversion — candidates assume 'trap' sounds more reliable or that informs use a different port, when in fact informs are the reliable, acknowledged mechanism and both use UDP 162.
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
✓
Traps are unacknowledged notifications sent from the SNMP agent to the manager.
Option A is correct because SNMP traps are asynchronous, unacknowledged notifications that an agent (or managed device) sends to a manager on UDP port 162 without expecting any reply. Option B is correct because SNMP informs are also notifications, but they are acknowledged: the manager must send a Response PDU back to the sender, and the sender retransmits if no acknowledgment arrives within a timeout. Option C is correct because informs are delivered to the manager on the same well-known UDP port 162 used by traps; the difference is the acknowledgment behavior, not the transport port. Option D is not correct because traps are actually less reliable than informs—traps are fire-and-forget with no acknowledgment, and SNMP does not assign them higher priority. Option E is not correct because informs require the sender to keep state (storing the request and waiting for a response, with retries), so they consume more memory and processing than traps, not less.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Traps are unacknowledged notifications sent from the SNMP agent to the manager.
Why this is correct
Traps use UDP port 162 and the agent fires them without awaiting any response, so delivery is never guaranteed. This satisfies the stem's requirement for a true statement about trap behaviour: the manager sends no acknowledgement, unlike informs, which the receiver must confirm.
- ✓
Informs are acknowledged notifications that require a response from the manager.
Why this is correct
Informs demand a response from the manager, unlike unacknowledged traps, satisfying the stem's requirement for acknowledged notification behaviour. The agent retransmits an inform until it receives confirmation, giving reliable delivery that traps cannot provide. This acknowledgement mechanism is the defining operational difference between the two message types.
- ✓
Informs use UDP port 162, the same as traps.
Why this is correct
Both traps and informs are received on UDP port 162 at the SNMP manager. The distinction lies in reliability, not transport: informs are acknowledged by the manager, whereas traps are unacknowledged. This statement correctly confirms the shared destination port, satisfying the question's requirement for a true claim about trap and inform operations.
- ✗
Traps are more reliable than informs because they are sent with a higher priority.
Why it's wrong here
Traps are unacknowledged and fire-and-forget, so the sender never learns whether the manager received them; informs are acknowledged, making them the reliable mechanism. Priority plays no part in either PDU. Traps suit high-volume, low-value notifications where losing an occasional message is acceptable.
- ✗
Informs consume less memory and processing than traps because they do not require state tracking.
Why it's wrong here
Informs require the sender to retain each notification until the receiver acknowledges it, consuming more memory and CPU than fire-and-forget traps. The statement inverts this. It tempts because traps genuinely avoid acknowledgement state, so if the question asked which mechanism is lighter on device resources, traps would be the answer.
Visual reference
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Same concept, more angles
1 more way this is tested on 350-401
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which two statements about SNMP trap and inform operations are true? (Choose two.)
hard- ✓ A.An SNMP inform request is acknowledged by the manager with a response PDU.
- B.SNMP traps are more reliable than informs because they use UDP port 162.
- C.Both SNMPv1 and SNMPv2c support the inform operation.
- ✓ D.Informs consume more network bandwidth and memory resources than traps.
- E.Traps are sent from the manager to the agent to request configuration changes.
Why A: Option A is correct because an SNMP inform request is a confirmed notification: the receiving manager must reply with a Response PDU (using the same request-id) so the sender knows the notification was received. Option D is correct because informs require the sender to retain the notification in memory until the acknowledgment arrives and to retransmit if no response is received, adding bandwidth and memory overhead compared with unacknowledged traps. Options B, C, and E are not correct: traps are less reliable than informs since they are unacknowledged, SNMPv1 does not support the inform operation (it was introduced with SNMPv2), and traps are sent from an agent to a manager, not from a manager to an agent to request configuration changes.
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.