As per the "official" release.
When feature is enabled, your internet traffic will be protected by a security ready DNS server. This feature provides Anti-Phishing to protect your Internet connection from fraud and navigation improvements such as auto-correction of common URL typos.
When DNS Relay is enabled along with Advanced DNS feature, your workstations on the network that are obtaining an IP address from routerís DHCP server will obtain 192.168.0.1 (routerís IP address). However, traffic will still be protected.
Although Advanced DNS feature is enabled, DNS IP address of your workstation can still be modified to the DNS server IP you desire. Please note that the router does not dictate the DNS name resolution when DNS IP address is configured on the workstation.
If you selected this option and have VPN or Intranet setup in your network, you can disable Advanced DNS service if you experience connection difficulties.