DNS: Why It’s Important & How It WorksThere are a couple of tools that users can use to find better or faster working DNS IP Addresses to use instead of automatic default ISP addresses that are handed out by the ISP.
1. Download one of the following to your Mac or PC:
Gibson Research Domain Name Speed BenchmarkGoogles Open-source DNS Benchmark Utility2. Install the program on to the Mac or PC.
3. Directly connect one wired LAN pc to the ISP modem. Disconnect any external routers from the ISP Modem. Only test with PC and ISP modem directly connected. (This eliminates any un-necessary router processing while testing and generating false results.)
4. Run the program. Should take about 5 minutes or less.
5. The program should find other, better or faster working DNS IP addresses. Write these addresses down.
6. Disconnect the PC from the ISP modem and re-connect the router to the ISP modem and re-connect the PC to the router.
7. Log into the routers web page and under Setup/Internet/Manual settings, input the 2 best DNS IP addresses into the Primary and Secondary field boxes. Save Settings. Reboot Later if this option is available.
8. Under Setup/Networking, disable DNS Relay. This option can be left enabled if connections fail or web sites fail to connect correctly. Preferred mode is disabled. Save Settings.
9. Reboot the router and
ALL connected client devices or flush and clear
ALL client device DNS cache.
10. After the router reboots, test Internet speeds and Internet web site connections for functionality. Should be good to go.
NOTE: Be aware that these DNS IP addresses could be changed with out notice, so it all of a sudden you are not getting web site connections. Revert back to your ISP DNS IP addresses and test again. If it works again with ISP DNS, then re-run the Name Bench program to re-acquire new DNS IP addresses.
It's recommended to use default ISP DNS addresses that your ISP automatically sends to modems and routers. Especially for troubleshooting. If your not an advanced user, then keep with the default ISP DNS IP addresses.
Other Security DNS Service Sites:
Norton ConnectSafe https://www.opendns.com/welcome/To properly test whether or not your OpenDNS settings are working on your router use the link and if a big check mark appears then the OpenDNS settings are good.
Other sources:
http://beebom.com/2015/06/best-dns-serversFYI:
DNS Name Resolution and D-Link Routers FAQ Enjoy.