APM DNS Mac OS - Not Working

Has anyone encountered an issue with DNS not working via Mac OS, but works on Windows - all versions? I have a network tunnel with several IP Addresses pointing to a customer environment - these IP's all use Host Entries to resolve the names as their isn't any DNS available.

I have another bank - a demo environment - that has a DNS server attached and I have it configured. When a Mac connects - it can ping the server without an issue, but will not resolve the name when trying to access the server. Attempting to get their by IP is also an issue.

Any thoughts?

Thanks!

DJL