According to the plugin:
The following environment variables are used
ping_args - Arguments to ping (default "-c 2")
ping_args2 - Arguments after the host name (required for Solaris)
ping - Ping program to use
host - Host to ping
Configuration example
[multiping]
env.host www.example.org mail.example.org
where do i specify the [multiping]
You should write this configuration into a new file located in
/etc/munin/plugin-conf.d
or add these two lines at the end of file
/etc/munin/plugin-conf.d/munin-node