Actually, checking my Telegraf config, it pings every 60s, sending 4 packets with a timeout of 2 seconds. The Grafana display was set to 5min updates but it doesn't have to be. Telegraf can also output direct to MQTT.
sudo journalctl -u node-red -f
Where node-red is the name of the systemd job that starts node-red on boot. All logs on Linux systems running systemd should be visible using that command, just replacing the name. You can easily add your own logs as well, if you dig out my post on running IMAPFILTER or NMAP, you will see examples, really useful for running CRON batch jobs and managing log output.
That's OK, I get that there is a need, I was just pointing out that there are better ways to fulfil that need than using Node-RED which might, itself, be part of an issue. For monitoring, it is better to use tools that are dedicated to that purpose.
On my systems, I use the home server to be the central hub. It runs Telegraf, InfluxDB, Grafana, Node-RED, Mosquitto. Telegraf pings a load of endpoints both inside and outside the network and records that to InfluxDB. So, if I can reach Grafana, I can see what is and isn't working.
But Ping only reaches the network card, it is no guarantee that the network is actually working or that the services above the network layer are actually doing anything.
To deal with that, I have every device and service that supports MQTT sending out keepalive pings around every 50 seconds (just under a minute). Each with an LWT. The pings send "Online" and the LWT sends "Offline". So that includes all of my home-made sensor platforms and node-red. In fact, node-red sends a number of regular pings, one for itself but others for services that don't directly support MQTT. Such as my RFXtrx433e.
In addition to the Telegraf pings, I also run a periodic NMAP scan of the network, the results of which are read by Node-RED and incorporated into my network device, and known devices tables (and corresponding MQTT topics). NMAP does a lot more than just a ping. In my case, it tracks the responsiveness of the device which can be useful when trying to track down a network problem. It also lets me find new devices on the network so that I can identify them.
With my router, WiFi AP and NAS, I've also experimented with SNMP monitoring. But as yet, I've not really had enough incentive to do that much. One of the big sticking points with SNMP and Node-RED is that some outputs from SNMP are big numbers in a format that JavaScript doesn't support (variable length numbers up to 64bits). I've not managed to work out how to decode them yet.
I also use Telegram for alerting. Though you might want to have two bots, a chatty one and a quiet one. The quiet one tells you just about really important things like the door-bell, or the front door being left open. The chatty one should also send out regular messages so that you will be able to see if things have suddenly gone quiet. So my chatty bot tells me when lights go on or off, if humidity goes outside normal ranges, when movement is detected, ...
Oh, at it is also worth knowing that Grafana has a Telegram alert extension. Very useful.
