184.108.40.206 have become the de facto standard for DNS servers in recent years. If you have no issues, you're welcome to use these.
If you're seeing DNS issues, we can also suggest trying other alternatives. We peer directly with Level 3 Communications so we can also recommend using Level 3's anycast DNS servers:
Still seeing issues? Open a support ticket with our engineering team if you need help in further diagnosing DNS issues. We may ask for
traceroute information at the time of the issue to diagnose problems from our side of the network.
If you're using a MacStadium firewall solution and you're pushing the limits of the firewall (e.g., 650 Mbps on a Cisco ASA5540), that might be why you're seeing high packet loss.