Giga Hub dns relay filtering

[jjjjjj]

It has been reported in other posts here that the Bell Giga Hub modem (sagemcom) acts as a dns relay for its dhcp clients.  This means that the ip address of the Gig Hub is sent to all dhcp clients as the primary dns server.  It is not possible to disable this.

I have discovered that the Giga Hub is filtering/blocking some name requests.

You can demonstrate this yourself by logging into the Gig Hub and going to "Advanced tools and settings \ Tools -- Utilities \ Nslookip".

If you do nslookup queries for www.example.com  and www.example.org then you will get the response "Error: Cannot resolve specified hostname".

If you query the upstream dns servers directly (you can do that from the command line), then they will resolve those names.

I don't like this behaviour at all.  It seems to be a misconfiguration.  The modem should not be silently filtering my dns queries.

Short of abandoning the dhcp server on the Giga Hub, is there anything I can do about this?

Note that I called Bell to report this issue.  That was not a fun experience.  I was kept on hold for more than 40mins.

[ZaneP]

You can't assign your own local dns server on a Bell gateway modem.

I think you'll need to attach something like a pi-hole server (or your own router): turn off DHCP on the Gigahub, let the pi-hole handle dhcp and be the dns server. 

[jjjjjj]

Thanks for your reply.

I'm not interested in setting up my own local dns server.  I agree that I may need to start using my own dhcp server to work around the issue with the Giga Hub.

Do you think it makes sense that the modem does not resolve the names www.example.com  and www.example.org?

To me, that suggests that the dns relay being done by the modem is not working correctly.

[ZaneP]

Yes, you could use your own router's DHCP server to to assign local addresses. But without a local DNS server to handle dns requests from the LAN devices you're pounding on that router for DNS resolution, correct?

Also, just the usual caution on the potential downside of connecting a router to a modem that has no true bridge mode.

I don't know why those hostnames are being resolved correctly. If it's mission-critical, I suggest you post on DSL Reports, Bell forum. You'll find the depth of technical knowledge for this issue may exceed the front-line 1st-level support from Bell. Can't say for certain, but it's worth a try. Post here: https://www.dslreports.com/forum/sympat

Hopefully others will contribute to this thread. Good luck with everything.

[Terry3000]

I am in process of rebuilding my network after adding a GigaHub. I want to use an IP addressing scheme where I custom choose the 3rd quartet. No problem GigaHub supports that, just change it in the DHCP config.. I now want to add a Pi-Hole server, while continuing to use the GigaHub DHCP. My problem is that the DHCP will not allow me to specify my Pi-Hole as the DNS server, It defaults to X.X.X.1. Next attempt is to set the Pi-Hole as by DHCP server, however the GigaHub reverts to its standard 192.168.2.1 address, meaning that my default gateway would need to bridge subnets. (3rd Quartet is not 2). Does anyone else have experience or suggestions how to resolve this.Other than stay with a 192.168.2.X subnet that the GigaHub defines.

[Wakka197]

That is intresting

[Vanadiel]

It makes sense to some extend. I don't think the modem  is filtering the DNS queries. 

Likely the DNS records for those 2 examples are not existent on the DNS server used, because they are test domains so they decided to filter them out. In the end, the modem does not resolve anything it's the DNS server that resolved it.