I've used cPanel for years without this kind of mystery reconfiguration. @gnif has some forensic work to do from the sounds of it. Not that he won't find it was some 'unscheduled help' from the hosting company.
What they failed to mention was that
they deployed the server to use DHCP, they then moved away from DHCP when they moved data centers, and never updated Dave's "managed" server, so when their DHCP server went offline, so did this (and how knows how many more) server when the DHCP lease expired.
They then tried to perform a `yum update`, which failed as cPanel blacklists the perl packages. They assumed this was due to the "incompatible" CentOS repositories. Rather then contacting Dave or myself about what they wanted to do, they forcibly removed the kernel and swapped it out for a different one. Their reason for changing the kernel was valid, but the assumption that they could just do this was extremely unprofessional.
Edit: I just confirmed by restoring the config from backup that it was indeed configured by HG to use DHCP# cat etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE="eth0"
BOOTPROTO="dhcp"
IPV6INIT="yes"
MTU="1500"
NM_CONTROLLED="no"
ONBOOT="yes"
TYPE="Ethernet"
Here is the bash history of their session and my comments.
501 2018-03-12 07:54:25 yum list installed | grep *redacted*
502 2018-03-12 07:54:34 yum erase kernel-*redacted*
503 2018-03-12 07:55:10 yum erase kernel-*redacted* kernel-*redacted*
504 2018-03-12 07:55:18 yum update kernel
505 2018-03-12 07:56:52 reboot
Note they did not even check why it couldn't talk to the network, they just blindly assumed a kernel fault, and uninstalled it
506 2018-03-12 07:58:28 ping [url=http://www.goog]www.goog[/url]
507 2018-03-12 07:58:33 ping [url=http://www.google.com]www.google.com[/url]
508 2018-03-12 07:58:37 history
509 2018-03-12 08:00:14 yum repolist
Ok, failed to ping google... checked bash history, not sure why. Then checked the repositories installed into yum.
510 2018-03-12 08:06:05 cat /etc/sysconfig/network-scripts/ifcfg-eth0
Great, ok, finally looking at the network configuration. Anything else related to altering this file is missing from the history, I can only assume it was done in another terminal, or remote transfer via SCP or similar.
511 2018-03-12 08:10:31 for ip in $(ip a s eth0 | awk -F'[ /]' '/inet.*global/ {print $6}') ; do echo -ne "${ip}\t" ; ping -c3 -I ${ip} 8.8.8.8 2>&1 > /dev/null && echo "UP" || echo "DOWN" ; done
512 2018-03-12 08:13:34 yum update
A simple script to check for connectivity and then... `yum update`
The server was back online at this point... their work was done, if they wanted to do anything more they should have checked first.