DNS Issues with CGN3ACR and external router

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I've Been Here Awhile
Posts: 3

DNS Issues with CGN3ACR and external router

I'd love to get someone's help on the following configuration:

 

1) CGN3ACR is setup in bridge mode

2) DLINK DIR-859 setup has the Google DNS - 8.8.8.8 and 8.8.4.4

3) When I renew the IP Addresses on my devices, it assigns the above DNS + 2 Rogers DNS (64.71.255.204 & 64.71.255.198)

 

Can someone PLEASE let me know why the last 2 Rogers DNS?  I've not been able to find anyone with this issue online.  Appreciate the help in advance.

 

 

 

*** Edited Labels ***

Resident Expert
Resident Expert
Posts: 6,026

Re: DNS Issues with CGN3ACR and external router

Yup, that's a bit strange.  Sure that the modem is running in Bridge mode?  If you have a CGN3ACSMR, you can log into the modem thru the router by using 192.168.100.1.  If the modem is in Bridge mode you should see only the following main entries at the top, STATUS, BASIC, ADMIN.  If you see anything more than that, your modem is in Gateway mode.  Not trying to insult anyone's intelligence here, just covering all bases.  Past problems have included this very item, thinking that the modem is in Bridge mode when its still in Gateway mode.

 

Beyond that, take a look at the following Microsoft page:

 

https://technet.microsoft.com/en-ca/library/cc781949%28v=ws.10%29.aspx

 

With that page in mind, start a command prompt using Admin credentials (Run as Administrator)

 

type:

 

ipconfig /flushdns

ipconfig /release

ipconfig /renew

ipconfig /all

 

The last command will display all of the network details including the DNS servers.  The microsoft page doesn't indicate if the actual DNS resolver address is removed.  So, give that a go and see what turns out.

 

Is the D-Link router model number correct?  Can't seem to find that model on the D-Link site to check the manual.



I've Been Here Awhile
Posts: 3

Re: DNS Issues with CGN3ACR and external router

Thanks for the reply!  Let's start off by saying that I only have Macs so I can't run those commands.  Any equivalents in terminal that would allow that?

I'm certain that I'm in Bridge Mode since what you've indicated is all I have (and I cannot get there via 192.168.1.1 only via 100).

 

My bad on the router - it's actually DLINK DIR-859 (which I've edited in the original post).  This has been bugging me for the last 4 months and would love some sort of resolution!!!

Resident Expert
Resident Expert
Posts: 6,026

Re: DNS Issues with CGN3ACR and external router

Mac's don't have a similar DNS flush capability? Have a look at the following page for similar Mac commands:

 

https://coolestguidesontheplanet.com/clear-the-local-dns-cache-in-osx/

 

Typically, when you enter DNS entries in the router, they take precedence over the ISP DNS.  So, it would be unusual for any end device to show the Rogers DNS address at the same time.  Now, reading thru the 859 user manual I see that there are IPV4 and IPV6 settings for the router.  I had thought that the IPV6 DNS address would be different, I'm sure that they are different, but I wonder at the present time if the address that Rogers advertises is the same as its IPV4 address.  Speculation on my part.  Given the current state of IPV6 with Rogers unless you are running an IPV6 in IPV4 Tunnel at the present time, I would disable all IPV6 in the router except for the firewall and disable IPV6 in the MAC.  Then after running the appropriate command to clear the DNS cache, reboot the router and mac and see what turns up after the reboot.

 

Edit:  Have a look at page 56 and 57 of the user manual.  On page 56 is an Enable DNS Relay setting.  Its shown on the graphic on page 57.  What this indicates is:  Disable to transfer the DNS server information from your ISP to your computers. If enabled, your computers will use the router for a DNS server.  This is located in the Network.... Network Settings section.

 

So, I would speculate that you have to enable this setting to override the ISP DNS data with the preferred DNS address.



I've Been Here Awhile
Posts: 3

Re: DNS Issues with CGN3ACR and external router

Thanks for the tip - by enabling the DNS relay, it uses my LAN IP address (192.168.0.1) and then from the assignments properly are given to the device.  That said, I can't get to the internet with that turned on.  By disabling it, the devices are returned with 4 entries:  2 from the Google DNS (which I put in), in addition to the 2 from Rogers.  

Not sure if anyone else has had/have this problem with a DLINK router.  Appreciate any help.

Resident Expert
Resident Expert
Posts: 6,026

Re: DNS Issues with CGN3ACR and external router

Thats very odd to say the least.  Normally, on a router or modem, the minute that you key in an address into the DNS entry window, that takes precedence over the ISP DNS address.  Were you able to run a DNS flush on your mac?  Which DNS has precedence on your mac, google or the Rogers DNS?

 

What settings are available under the 859's Network .... Network Settings .... Advanced Settings?  Anything related to the DNS function?



Rogers Employee kr6
Rogers Employee
Posts: 40

Re: DNS Issues with CGN3ACR and external router

I am not famliar with DLinks settings, however some router have an option to pass on the ISP DNS in addition to the ones specified. I have seen this option on the General Setup or the DHCP Setup.

 

Another question, is what is the concern with having the Rogers DNS entries on your devices? These two additional DNSes will only be queried if both Google DNSes are not available (which is very unlikely). Even though they show up, they probably have never been used.