Mosquitto was installed correctly on the Cisco IR829 router as a Cisco IOx application. When the sensor is connected to the broker on the Cisco IR829 router with the default port, the connection is…

Question

Options

• AInsert in the IOS config: ip nat inside source static tcp <CAF IP> 1883 interface GigabitEthernet0
• BInsert in the package_config.ini file under section ports: tcp: ["8883"]
• CUse the correct username and password.
• DInsert in the package.yaml file under section ports: tcp: ["1883"]

• A
  11% (4)
• B
  8% (3)
• C
  55% (21)
• D
  26% (10)

Explanation

MQTT Error Code 5 specifically means "Connection Refused: Not Authorized," which is an application-layer rejection by the broker itself - meaning the network connection succeeded but Mosquitto denied it due to missing or incorrect credentials. This is a pure authentication failure, resolved by providing the correct username and password configured in Mosquitto.

Why the distractors are wrong:

• A (NAT/static mapping): A NAT issue would prevent the TCP connection from reaching the broker at all - you'd get a network-level timeout or refusal, not an MQTT Error Code 5. The sensor is reaching the broker.
• D (package.yaml port 1883): If port 1883 weren't exposed in the IOx package definition, the sensor couldn't establish any TCP connection to begin with - again, you'd see a network error, not an MQTT-layer error code.
• B (port 8883 in package_config.ini): Port 8883 is for MQTT over TLS/SSL; switching ports doesn't resolve a credentials problem and would actually require additional TLS configuration on the client side.

Memory tip: Think of MQTT error codes as HTTP status analogues - Code 5 ("Not Authorized") maps to HTTP 401/403. If you see it, always think credentials, not networking.

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