Potential DNS conflicts with new modem router combo

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I'm Here A Lot
Posts: 6

Potential DNS conflicts with new modem router combo

I'm a bit tired of technical issues with Rogers. For more than a year I had a SMC that gave me grief. I finally got a Cisco gateway and all was good for 6 months. My router is an ASUS RT-N66u and it ran beautifully with the Cisco gateway. 2 weeks ago my household updated our package and had to replace the Cisco gateway with the Hitron CGN2-ROG

 

In the passed 18 or so days we've had 2 occurences where we couldn't surf the web - on multiple laptops/devices we'd receive (could not connect to server) errors. The second time it happened I was mid-download with from various IPs. Even though we were unable to surf the web the downloads continued unimpeded. This is why I believe it to be a DNS issue.

 

I checked my router log for anything that stood out and I see a lot of entries containing 'dnsmasq-dhcp' occuring over the past few days.

 

I'd like to note that simply turned off the wireless function of the gateway. I assumed that was enough.

 

EDIT - The issues I'm having appear very similar to the one(s) in this topic: http://communityforums.rogers.com/t5/forums/forumtopicpage/board-id/Getting_connected/message-id/186...

 

 

***edited labels***

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Resident Expert
Resident Expert
Posts: 6,052

Re: Potential DNS conflicts with new modem router combo

Hi,

 

It would appear that you have three possible sources of DNS addresses, the CGN2, RT-N66u and finally the laptops.  Question is, which one is supplying your DNS address, and has something happened to it that you are not aware of? 

 

Looking at the CGN2 Manual page Page 48 Figure 12, you can enable the CGN2 to use your selected DNS address when the DNS box is checked, or use Rogers DNS by leaving it unchecked.  So, if you do nothing, you end up using the Rogers DNS.  The assumption here is that you have the CGN2 in Gateway mode.

 

REF:  http://setuprouter.com/router/hitron-technologies/cgn2-rog/manual-1028.pdf

 

Looking at the manual for the RT-N66u, there is only one space for the primary DNS address.  Given the lack of instructions in the manual, it would appear that if this is blank, then it uses the DNS address of the IP provider, which in this case is Rogers, if you have elected to leave the CGN2 DNS fields empty.  If you input an address into the N66u DNS address field, you have to reboot the N66u for the change to have effect. 

 

Lastly, there are the laptop settings.  I bring this up as there was a case very recently of an erroneous DNS address in the pc or laptop.  You have to drill down to the DNS address settings to determine what is set, Automatic DNS address from the router, or manual DNS address that you have selected.  Here is the link to the Microsoft page that describes how to get there:

 

http://windows.microsoft.com/en-ca/windows/change-tcp-ip-settings#1TC=windows-7

 

So, by reviewing all of those DNS sources you should be able to determine what device is providing the DNS address.  To confirm that, open a command prompt and type:

 

IPCONFIG/ALL

 

That will display your ethernet parameters including what DNS address is actually being used.  With that you can compare the address against the contents of the CGN2 or N66u address fields.  Here are the fields from all of the displayed IPCONFIG/ALL data on my pc, which shows the OpenDNS addresses:

 

DNS Servers . . . . . . . . . . . : 208.67.222.222
                                              208.67.220.220

 

From what I remember, I think there have been issues with DNS addressing from Rogers.  I don't use Rogers DNS so I can't personally confirm that.  A food for thought consideration is to put the DNS address in the pc and laptop so that in the event that your router is hacked and the DNS is changed without your knowledge, you will still be using the DNS address from the pc or laptop. 

 

So, have a look at the DNS address fields in the CGN2, N66u and pc/laptop and see what turns up.  Let us know what you find out.

 

 

 

 

 

 



I'm a Reliable Contributor
Posts: 348

Re: Potential DNS conflicts with new modem router combo

If you have a router then things will go more smoothly if you put your CGN2 into Bridge mode so that it only functions as a modem and not as a modem and router.  It doesn't look like you have done that.

Resident Expert
Resident Expert
Posts: 13,884

Re: Potential DNS conflicts with new modem router combo

I am running a CGN3 mind you, but with a N66U in AP mode.
Have a mix of STATIC devices with a manually entered in google DNS..

BUT, there are many devices (all the cells, 3 tablest, wifes laptop, and the smart TV) configured via DHCP and get the rogers DNS..and dont appear to have had any issues.

MIGHT be just CGN2 related.



I'm Here A Lot
Posts: 6

Re: Potential DNS conflicts with new modem router combo

Is there something specific one has to do to put the CGN2-ROG into bridge mode. I turned the wireless off (disabled it). Is there something else that needs to be done? I looked twice but I don't see anything remotely related to a defacto Bridge mode.

 

The CGN2-ROG is using the preset DNS servers: 64.71.255.204 & 64.71.255.198

 

The router DNS is set to 'Auto' which uses the ISP's DNS.

 

The laptops are a slightly different story. My laptop was set a few years ago to use OpenDNS (that may have changed with an update), while the other laptop just uses whatever it's told. The fact that they both have the same outage tells me that it's a modem/router issue.

 

I enterer the ipconfig /all command but there are no listed DNS servers. There is a DNS suffix field but it is blank.

Resident Expert
Resident Expert
Posts: 13,884

Re: Potential DNS conflicts with new modem router combo

I think it might be part in your setup.. that its not really in bridged mode, and that your ROUTER is then not getting the DNS properly now from the gateway, then not passing it on.

Lets get you in bridged properly.

 

When loged into the gateway.. you will want to go to STATUS > Capability

 

THere, you will want to UNCHECK the residential gateway function.

It will then reboot the gateway.

At this point, you would want to have already RESET your router, and then when the gateway comes back in bridged, the router should then PROPERLY connect to it, obtaining itself the ROGERS external IP as its outside address, the DNS, etc.



Resident Expert
Resident Expert
Posts: 6,052

Re: Potential DNS conflicts with new modem router combo

There is also the issue of whether or not you need to use the ports on the CGN2 for anything else other than the router.  That depends on your network layout in your home. Running in Bridge mode will preclude that I believe.  Gdkitty can probably confirm if in Bridge mode, only Port #1 is active?



I'm Here A Lot
Posts: 6

Re: Potential DNS conflicts with new modem router combo

OK, done. I disabled the residential gateway function. I assume it's normal that I can no longer log into the modem, and if I ever need to access the settings/logs I need to contact Rogers support, correct?

 

I won't really be able to say if this solved my problem but you helped me get the modem into bridge mode, and all seems well for now. Thank you.

 

 

Resident Expert
Resident Expert
Posts: 6,052

Re: Potential DNS conflicts with new modem router combo

To get back into the modem, press the reset button at the back for more than 10 seconds and release.  That should take you back into Gateway mode after it reboots.

 

If you bring up a command prompt and type in IPCONFIG/ALL you should see what DNS address your pc or laptop is using now, assuming that it or they are set to use an external address, not one that is entered into the DNS settings panel.

 

If the DNS field in the N66u is empty, then you should see the Rogers DNS address.  If you entered a primary DNS address into the N66u field and did a reboot for it to take effect, then you should see that primary address on the pc or laptop.



I'm Here A Lot
Posts: 6

Re: Potential DNS conflicts with new modem router combo

OK, sounds good.

 

ipconfig /all shows the router as the DNS server: 192.168.1.1

I'll give this setup a month or so and then I'm thinking I'll switch the router to Google/OpenDNS.