Well, that's already partly done. dnsmasq will fail to start with bind is running, as it should; based on port 53 already being in use or not.
As another option, you may also wish to switch dns=dnsmasq to dns=bind to use bind directly as a resolver. There are other reasons to have dnsmasq and/or bind installed, so even checking for existence isn't the right way to cover this.
Well, that's already partly done. dnsmasq will fail to start with bind is running, as it should; based on port 53 already being in use or not.
As another option, you may also wish to switch dns=dnsmasq to dns=bind to use bind directly as a resolver. There are other reasons to have dnsmasq and/or bind installed, so even checking for existence isn't the right way to cover this.