RAC Database Fail To Start Due To "terminating the instance due to error 119" error

Problem:
On a Linux 7, after system reboot I have an 11.2.0.3 RAC Database failed to start due to this error in the alertlog:
USER (ospid: 13324): terminating the instance due to error 119
Instance terminated by USER, pid = 13324
Cause:
While investigating I figured out that the SCAN name "rac1-scan" which is used in "remote_listener" initialization parameter is not pingable:
$ ping rac1-scan
ping: unknown host rac1-scan
When checked /etc/resolv.conf file I found the DNS server entry got removed:
$ cat /etc/resolv.conf
# Generated by NetworkManager
search preprod.mycompany.com

# No nameservers found; try putting DNS servers into your
# ifcfg files in /etc/sysconfig/network-scripts like so:
#
# DNS1=xxx.xxx.xxx.xxx
# DNS2=xxx.xxx.xxx.xxx
# DOMAIN=lab.foo.com bar.foo.com

Solution:
I restored the correct entries of /etc/resolv.conf which holds the right DNS server name
$ cat /etc/resolv.conf
# Generated by NetworkManager
search preprod.test.com$ 
nameserver 192.168.22.11
$ping rac1-scan