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Difficulty: MediumSNMP Operations, MIBs, Traps, Informs, and Version Differences

A network administrator is troubleshooting an issue where event notifications sent from a Cisco IOS XE router to a central Network Management System (NMS) are lost during network congestion. The router is currently configured with the following command:

`snmp-server host 10.10.20.50 traps version 2c public`

Which configuration change must the administrator make on the router to ensure that event notifications require application-layer acknowledgments from the NMS and are automatically retransmitted if dropped?

  1. Replace the keyword traps with informs in the snmp-server host command.Answer
  2. B
    Change the destination transport layer protocol from UDP port 162 to TCP port 161 in the snmp-server host command.
  3. C
    Append the overload keyword to the existing snmp-server host command statement.
  4. D
    Configure the router syslog severity logging level to 7 so that SNMP traps inherit TCP delivery mechanics.

Answer

Replacing the keyword 'traps' with 'informs' in the 'snmp-server host' command configures SNMP Informs, which require application-level acknowledgment from the receiver and support automatic retransmissions.
Configuring SNMP Informs instead of SNMP Traps provides reliable notification delivery. Unlike Traps, which are unacknowledged UDP messages, Informs require the NMS recipient to respond with an acknowledgment. If the router does not receive an acknowledgment within the specified timeout, it retransmits the Inform PDU.

Step-by-Step Solution

1
Analyze the operational difference between SNMP Traps and SNMP Informs.
SNMP Traps are unacknowledged notifications sent via UDP from an agent to an NMS. If a Trap packet is dropped in transit, the router has no mechanism to detect the loss or attempt retransmission. SNMP Informs require the NMS to reply with an SNMP response PDU to acknowledge receipt.
Understanding notification types is essential for selecting reliable event logging in network monitoring.
2
Identify the Cisco IOS syntax required to enable acknowledged notifications.
The command syntax `snmp-server host <ip-address> informs version <1 | 2c | 3> <community-string>` configures the router to send Informs rather than Traps.
Changing the keyword from 'traps' to 'informs' instructs Cisco IOS to store the notification in memory and retransmit it until an acknowledgment is received or the timeout threshold expires.

Key Concept

SNMP Traps vs Informs operational mechanics and Cisco IOS host configuration
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Topics

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

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