I have a few question regarding this topic.
First I'd like to ask how the IMC server should be added as a managed node for the 'Resource > Service Monitoring' to work properly?
I added IMC server using 'Resource > Add Device' just by using its IP address that is routable using the option: "Add the device regardless of the ping result". There is no SNMP nor telnet nor SSH authentication configured for this IMC server, so it is not recognized and was added as a Model: "Unknown Product", Device category: "Desktops" and permanently has status Unknown.
After this operation I'm able to setup 'Resource > Service Monitoring' without any errors or prompts mentioned in this topic.
My IMC server has 3 interfaces with of course 3 different subnets, among which only one has a gateway and default route.
I'd like to monitor eg. exernal DNS servers like cloudflare 1.1.1.1 and some websites but after I configured it I experience following problems:
1. for cloudflare dns Server Address:1.1.1.1 Response Time of DNS Service I get no data and cloudflare dns Server Address:1.1.1.1 DNS Service Unreachability Proportion is permanently 100%
2. also for some other Internet Service Unreachability Proportion I get 100% and Response Time of Internet Service no data
although I got ICMP replies for those services when I perform ping tests from servers CLI and also for other publicly available services like radius server I get RADIUS Service Unreachability Proportion 0% and Response Time of RADIUS Service some different values.
Also some of monitored Internet Services doesn't respond to ICMP requests although web services are running properly.
Is Internet Services monitoring based on http requests or just relies on ICMP test or both?
UPDATE1:
After I installed 'yum install bind-utils' DNS service is discovered but I still have an issue that DHCP server isn't detected by IMC Service Monitoring.
What system tools are used by IMC for Service Monitoring?
UPDATE2:
I did run tcpdump on IMC server and noticed that for:
Internet Services monitoring there are some tests that periodically communicate with websites at 443 port but alhough the communication is bidirectional not all websites are recognized by IMC server as running and no data are collected for those websites.
For DHCP service monitoring there are no packets that are send to DHCP server through interface that is connected to the network with DHCP server. So monitoring DHCP server doesn't work at all.