Only "Proxy to upstream DNS" mode works

[NadiaK]

MX-100, Firmware MX 14.42

My DHCP is configured with DNS option "Proxy to upstream DNS".

I would like use another DNS. But with options "Use Google public DNS" or "Specify nameservers" (list of Google and other tested servers) DNS doesn't work for users at all, even after reconnect and DNS cache clean up.

Who faced up with the same issue? What should I check?

Thank you in advance.

[ww]

Check with packet captures at the clients  and mx wan port if dns packets are send and received to the dns server you set.  

If clients are connected using meraki wifi you could also check wireless health for some  info

[antonis_sp]

Do you have any firewall rules? 

Make sure user traffic to udp port 53 is allowed.

[PhilipDAth]

>Make sure user traffic to udp port 53 is allowed.

You need to allow UDP and TCP 53.  UDP is used for queries with results under 512 bytes and TCP for larger results.

[Claes_Karlsson · Accepted solution]

Where have you started your troubleshooting? 

1. Test DNS lookup from the MX appliance status / tools page

 a) if this doesn't work, then you have some issues on the uplink.

 b) if this work, continue to the access layer

2. As NadiaK says, verify your DNS settings on the clients subnet on MX Configure / DHCP page.

3. Verify your DNS settings on the wireless network if your clients are connected wireless

4. Verify your firewall settings for the specific IP address of the DNS server and that DNS are allowed (UDP 53).

5. Try update your MX to the 14.53 version which is the stable release.

[NadiaK]

Thank you Claes_Karlsson. It was firmware issue.

After update everything works!