In general, the /etc/resolv.conf file on a compute node is managed by the node installer during provisioning.
Please see: https://support.brightcomputing.com/manuals/8.2/admin-manual.pdf#section.A.389
The "non-headnode" we're talking about, is that a login node perhaps? Else, what function does it serve?
If you wish to prevent changes to /etc/resolv.conf, you may use the FrozenFile directive in cmd.conf.
In "/cm/local/apps/cmd/etc/cmd.conf" add the line:
FrozenFile = { "/etc/resolv.conf"}
Once the above config line is added to cmd.conf, restart the cmd service.
# service cmd restart