Clients are bypassing the DNS set by the DHCP server set by Merlin

[iozzo]

I have an ASUS GT-AX6000 running on the latest stable version of Merlin. The router is configured as a DHCP server and, the DNS server is configured to be a pi-hole instance running on a mini PC.

Not sure why but, even if everything is correctly configured, the router is querying the DNS server. As a matter of fact, the Router is by far the most active client of the DNS server.
Not a biggie, afer all, if the router is acting as a DNS server but relies on pihole, unwanted traffic is still being blocked and pi-hole is not being bypassed .
But I am wondering why and what can I do to check which client is using the router as the DNS server. Is there a way perhaps with some logs ?

DNS is set under LAN -> DHCP Server -> DNS and WINS Server Setting
PIHole IP address is "Manually Assigned IP around the DHCP list" under LAN -> DHCP Server
Under WAN -> inernet connection -> WAN DNS Setting, the DNS Server as set to be Google (not pihole)

thanks in advance.

 

[iozzo]

Forgot to mention that I did check online and there are many people with similar problems where the router is the only client of the DNS. This is not my case, I can see plenty of other clients.

 

[dave14305]

Is DNS Director configured?

 

[iozzo]

DNS Director is Enabled ansd set to Global Redirection = Router. Moreover, the pihole MAC address is set down below with Redirection = No Redirection

 

[dave14305]

So some clients must be ignoring the DHCP DNS being offered and DNS Director is redirecting those queries to the Pi-Hole. In that scenario the router IP will appear as the client making the query.

 

[iozzo]

Which is great I guess, perhaps some client has a manual DNS set and ignores the DNS assigned by the DHCP. But how can I know which one ? Is there a log I can check ? I have far too many client to check and I would like to avoid checking each one.

 

[iozzo]

Ok, I managed to find it. Thanks a lot for your help. To be honest, I didn't even know what DNS Director was and that all these queries belonged to it.

 

[bennor]

Some comments. There is a basic setup guide (including DNS Director), with screen captures, for Pi-Hole on Asus-Merlin here:
https://www.snbforums.com/threads/pihole-dns.74646/page-3#post-712319

And make sure to set "Advertise router's IP in addition to user-specified DNS" to NO under the LAN > DHCP Server page.

 

[iozzo]

Yeah thanks. So I have just learned that Google Home appliances are hard coded to use google own DNS servers. It's fantastic that DNS director forces them to use pi-hole.

Thanks a lot for your help.

 

[bbunge]

Yeah thanks. So I have just learned that Google Home appliances are hard coded to use google own DNS servers. It's fantastic that DNS director forces them to use pi-hole.

Thanks a lot for your help.

You can simplify things by using Diversion on the router instead of a Pi-Hole. Diversion can use the same block lists as Pi-Hole.
Also, it may be a good idea to use a filtering DNS resolver such as Quad9 or Cloudflare Security (1.1.1.2 and 1.0.0.2) on the router WAN setup.

 

[iozzo]

Yeah I am using Cloudfare Security under WAN settings. As per Diversion, I was actually using pi-hole on the asus router but it required a USB key connect which eventually broke (it was a cheap one, my bad). After that I simply installed it on a mini PC I use for plex and for Unify Network Controller which is running 24/7.

 

[bennor]

Yeah thanks. So I have just learned that Google Home appliances are hard coded to use google own DNS servers. It's fantastic that DNS director forces them to use pi-hole.

You can block the Google DNS servers using the LAN - Route section to prevent devices from using them.

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