DNS Priority (Windows 10 vs Router/Modem)

fwshaw · 29 Nov 2017

OS: Windows 10, version 1709
Router/Modem: Arris (Comcast) TG1682g

I have a question about which DNS IP address has priority.

The router has a fixed DNS IP of 75.75.75.75 (Comcast). It appears from looking at the router software/firmware and comments on the Comcast user's forum it is not possible for me to change the DNS IP of this router.

I've set Windows DNS IP to 9.9.9.9 (Quad9). I want to use the DNS servers at 9.9.9.9; I do not want to use the DNS servers at 75.75.75.75

My question is: When my Windows 10 send a DNS request to 9.9.9.9 does the router's DNS setting (75.75.75.75) override the Windows DNS address? Or is the DNS request sent to 9.9.9.9 in spite of the routers DNS setting?

Thanks for your wisdom and insights.

Samuria · 29 Nov 2017

No windows in full control it goes to the dns set in its properties

bro67 · 01 Dec 2017

It is fixed so that the phone side of that eMTA will work. If you need the phone, keep the TG1682g for that. If you want to use your own DNS, place a Gateway behind that eMTA or get the proper splitter, connect the eMTA to the first leg of the splitter and on the other, a decent modem, Gateway and Access Point, so that you have more flexibility on your network.

fwshaw · 01 Dec 2017

Many thanks for your comment and insight. I am using the TG1682G router/modem for phone service. Since that means the routers DNS IP address is fixed, does that also mean my computer (laptop) DNS server access is also fixed to 75.75.75.75 (Comcast) even though Windows 10 DNS address is set to 9.9.9.9?

Also when you use the term "a Gateway behind" do you mean between the Internet connection and the eMTA?

TairikuOkami · 01 Dec 2017

fwshaw said:

I have a question about which DNS IP address has priority.

If in doubt, you can check your DNS servers using DNS leak test or BrowserLeaks.

bro67 · 01 Dec 2017

fwshaw said:

Many thanks for your comment and insight. I am using the TG1682G router/modem for phone service. Since that means the routers DNS IP address is fixed, does that also mean my computer (laptop) DNS server access is also fixed to 75.75.75.75 (Comcast) even though Windows 10 DNS address is set to 9.9.9.9?
Also when you use the term "a Gateway behind" do you mean between the Internet connection and the eMTA?

Again. If you want to be able to set your own DNS and not have to use the eMTA with Comcast’s DNS, you can either put them in static and hope that a driver update does not reset them. Ot go purchase your ownModem, wired Router/Gateway and a Access Point. That will give you the most flexibility if the time should come that you have to replace any of those three items, including having a better CPU&RAM for the Router and same for the Access Point.

You want to just go with your idea, that is fine temporarily, just heedehat I posted.

fwshaw · 02 Dec 2017

Got it...thanks to all for your insight and information.

cereberus · 02 Dec 2017

As a rule, DNS set in Windows (with static IP etc) override a router DNS. However, some routers intercept the Windows DNS making the router DNS take priority. This is pretty rare though.

Most routers in UK lock down DNS on router but do allow you to use a Windows DNS instead. I use a chromecast dongle and you have to bypass router DNS to cast videos from a VPN. I got round this by having a second non ISP supplied router connected LAN/LAN and set that routers DNS accordingly. That way I could easily flip flop between DNS needed for VPN and DNS needed for normal internet traffic simply by connecting to appropriate router via wifi.

If router does intercept DNS, then really only option is to use a genric non ISP router.