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DNS Resolution

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• February 16, 2017 at 5:01 pm #1199
  Solus

  Participant

  Hi,

  I just purchased a TP-LINK Archer C7 with PCwrt this week. I have everything set up and working with the router. I turned on Parental Controls and set up the default profile with Parental Controls disabled and a “Kids” profile with a whitelist. All my devices seem to be working with this setup, except one. My Macbook Pro (mid-2010 model, MacOS 10.12.2) does not resolve DNS addresses over either wi-fi or ethernet. In both cases, I’ve tried to manually set the DNS server to my router’s IP address or even directly to the Google DNS (8.8.8.8) for both the wireless and ethernet profiles, but nothing seems to be working. If I turn off the whole Parental Controls system with the button at the top of the tab, the laptop works fine. Do you have any idea why this might be happening?

  February 16, 2017 at 7:07 pm #1200
  support

  Keymaster

  Does it work when you have the Macbook Pro in the default profile, where parental control is disabled?

  February 16, 2017 at 7:46 pm #1201
  Solus

  Participant

  Should have been more clear – the macbook is in the default profile (to be precise, I haven’t assigned it to any profile).

  February 16, 2017 at 11:18 pm #1202
  support

  Keymaster

  When parental control is enabled, DNS lookup is forced to go through the server IPs selected for the profile. Maybe your Macbook Pro doesn’t like that.

  Did you try setting the Macbook Pro DNS server to the pcWRT router IP address (and omit the secondary DNS server)?

  You may also try to look at what DNS server the Macbook Pro is really using by loading this URL in your browser: http://myresolver.com. Of course you have to disable parental control at the router level in order to do that. Then change the DNS servers for the router (on the Internet Settings page), and see if that has any effect on the DNS server actually used by the Macbook Pro.

  Keep the DNS server setting on the Macbook Pro point to the pcWRT router while you do these tests.

  February 17, 2017 at 3:59 pm #1206
  Solus

  Participant

  Ah, figured it out. When I disabled parental control and then tried myresolver.com, I found out that the DNS server the mac was using was an openDNS server, no matter what address I used in the network settings. Then I remembered that I had installed DNSCrypt on my mac a long time ago. Once I disabled the DNSCrypt software, everything on the mac now behaves normally, even with the Parental Controls turned on.

  Out of curiosity, when the router profile is set to “OpenDNS Family Shield”, there is an IP address listed: 208.67.222.123. But When I use myresolver.com, the DNS server that my computer uses is a different openDNS server (208.67.219.17 or 208.67.219.15). I presume this is fine since they are all openDNS servers, but I’m wondering if this is normal. Also, I noticed when I set the profile to “Google Public DNS”, the DNS server my computer uses goes to a completely difference address (74.125.80.65 or a comcast DNS server). Why isn’t this setting working as expected?

  February 17, 2017 at 9:35 pm #1207
  support

  Keymaster

  OpenDNS uses a technology called Anycast to provide fast DNS service with redundancy. The IP addresses you use are the Anycast addresses. The DNS requests, after they are received, are routed to the backend, which uses unicast addresses to query downstream DNS servers. Those DNS servers will see different IP addresses. I guess Google works pretty much the same way.

  For more info: https://blog.opendns.com/2013/01/10/high-availability-with-anycast-routing/

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