1. Proposed title of this feature request

Have a way to specify/limit the interface to be used by machine-config-operator coredns-corefile.yaml

2. What is the nature and description of the request?
We have the need to be able to expose a dns service running on a a 3 node cluster (masters == workers) using MetalLB. Right now the coredns using the Corefile that is generated from this template: https://github.com/openshift/machine-config-operator/blob/master/templates/common/on-prem/files/coredns-corefile.yaml
is listening on all interfaces an exposing the service on a dedicated nic via metallb fails with {{}}

Warning AllocationFailed 121m metallb-controller Failed to allocate IP for "openstack/dnsmasq-dns-ctlplne": port UDP/53 is already in use on "192.168.130.71"

{{}}
3. Why does the customer need this? (List the business requirements here)
For OpenStack NextGen where services are hosted on OCP we need to be able to expose a DNS server via MetalLB on dedicated interfaces.

4. List any affected packages or components.

MCO / https://github.com/openshift/machine-config-operator/blob/master/templates/common/on-prem/files/coredns-corefile.yaml

not sure if others