Nagios Support Forum

Hi all, I’m having an issue in Nagios XI where some Linux hosts are being reported as DOWN even though they are clearly reachable. NRPE-based service checks like CPU, disk, and load are all returning OK, I can SSH into the servers without any problem, and pinging the hosts directly from the Nagios XI server works fine. Despite this, Nagios still marks the host itself as DOWN, which causes service alerts and incorrect notifications. This seems to affect only certain hosts, and it started after a recent network change involving NAT. I’m not sure if this is related to the default check-host-alive command, host templates, or how Nagios is handling ICMP for these systems. Has anyone run into a similar situation or can point me in the right direction to fix this?
Geometry Dash

Hi @Mikasa23 ,

You could try to see if the broken and working host checks are using different host check commands or templates. Depending how the hosts were added, they might be different. You could also try changing them on the broken ones to see if that helps.

This document might be of some help to you: https://assets.nagios.com/downloads/nag ... _In_XI.pdf

How are you checking the hosts that are failing and not failing? You can test from the shell.
I've seen check_ping fail and had to switch to check_icmp in the past. It was a bit strange...