Related to:

Geneos 

Using the Trapmon plugin in Geneos where SNMP traps show an IP address in the Source column instead of the expected hostname.

Problem:

• Inconsistent Source values (mix of hostname and IP).

• Downstream applications require hostname but receive IP for some events.

• Confusion due to alternating hostname/IP for the same device.

Possible cause(s):

• Root Cause 1: The sending device cannot consistently resolve its own hostname and falls back to sending its IP address.
• Root Cause 2: DNS reverse lookup is not properly configured or is intermittently failing.
• Root Cause 3: The device is configured to send traps using IP instead of hostname, or has mixed configuration.

Possible solution(s):

• Solution Root Cause 1: Verify the sending device’s DNS configuration and ensure it can consistently resolve its own hostname. If hostname resolution fails, the device may fall back to sending its IP address.
• Solution Root Cause 2: Check forward and reverse DNS records for the device. Confirm that the Geneos server can resolve the device IP to hostname using nslookup. Fix any DNS inconsistencies or timeouts.
• Solution Root Cause 3: Review the SNMP trap configuration on the device and standardize it to send either hostname or IP consistently, depending on your requirement.

Related article(s):

• https://docs.itrsgroup.com/docs/geneos/current/collection/trapmon/index.html#Heading-introduction 

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