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Difficulty: Very hardSNMP Operations, MIBs, Traps, Informs, and Version Differences

An enterprise network administrator is updating the SNMP monitoring configuration on a Cisco IOS XE core router to meet strict security and monitoring compliance standards. The updated policy mandates two specific requirements for outbound system event notifications sent to the central Network Management System (NMS):
1. All notifications must be encrypted using AES privacy and cryptographically authenticated using SHA.
2. Outbound notifications must require explicit application-layer acknowledgments from the NMS, causing the router to resend notification packets if no acknowledgment is received.

Which combination of SNMP protocol settings and message types must be configured on the router to fulfill both requirements?

  1. SNMPv3 operating at the authPriv security level utilizing SNMP InformsAnswer
  2. B
    SNMPv3 operating at the authNoPriv security level utilizing SNMP Traps directed to UDP port 161
  3. C
    SNMPv2c configured with a read-write community string utilizing SNMP Informs over a TCP connection
  4. D
    SNMPv3 operating at the noAuthNoPriv security level utilizing SNMP Traps with configured retry timers

Answer

The router must be configured for SNMPv3 operating at the authPriv security level using SNMP Informs.
SNMPv3 with the authPriv security level supports both authentication (SHA/MD5) and encryption/privacy (AES/DES). SNMP Informs provide reliable notification delivery because the managed device holds the notification in memory and retries transmission until an explicit acknowledgment PDU is received from the NMS.

Step-by-Step Solution

1
Evaluate the security requirement (authentication and encryption).
Identify that SNMPv3 defines three security models: noAuthNoPriv (no security), authNoPriv (authentication without encryption), and authPriv (authentication with encryption).
To satisfy the mandate for SHA authentication combined with AES encryption, the authPriv security level must be selected.
2
Evaluate the notification delivery requirement (acknowledgments and retries).
Differentiate between SNMP Traps and SNMP Informs.
SNMP Traps are unacknowledged notifications (fire-and-forget). SNMP Informs require the receiving NMS to return an acknowledgment PDU; if the agent does not receive an ACK within the timeout period, it retransmits the Inform.
3
Synthesize the security and operational mechanics requirements.
Selecting SNMPv3 authPriv with SNMP Informs satisfies both cryptographic security and reliable delivery criteria.
Combining authPriv (for SHA/AES) and Informs (for acknowledged delivery) satisfies all security policy constraints.

Key Concept

SNMPv3 Security Levels (authPriv) and Notification Reliability Mechanics (Informs vs Traps)
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Topics

SNMP Operations, MIBs, Traps, Informs, and Version Differences

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