Strange DNS Problems

[NunoFlora]

I have a DNS problem in a network of 500 users, some devices connect to the wifi in one of the ssid and after connection ok they use chrome that tells them the dns did not respond i check the logs in meraki and see "DNS server did not respond".

I'm using google 8.8.8.8 and 8.8.4.4 but for some reason it gives me this errors but I can use a computer and ping 8.8.8.8 and 8.8.4.4 no problem but can't get dns in chrome our other web browser.

[alemabrahao]

Is The Client IP assignment  NAT mode or Bridge mode?

[Inderdeep]

@NunoFlora : Check this thread 

https://community.meraki.com/t5/Wireless-LAN/Weird-DNS-Issues/m-p/5352#M970

[PhilipDAth]

If you use nslookup, can you resolve a DNS name?

Chrome changed over to using DNS over HTTPS at some stage, so it may not be sending DNS queries as you think.  I think it was optional initially and then became the default.  You could try a test and disable DNS over HTTPS on one machine and see if that changes the problem.

https://pureinfotech.com/enable-dns-over-https-chrome/ 

Are you using any third-party filtering software, either for DNS or HTTPS?

[MerryAki]

I would also mention DNS over TLS as a possible problem. Try to do a trace route anc check for rules that block traffic to the DNS Server/s.

Another thing that might be required at some point is DNSSEC, give 9.9.9.9 a chance. (Cloudflare is of course a good one, too, but not in terms of security and threat defending)

[securingnimbu5]

@MerryAki I have to agree with you here.

My thoughts:

If he can ping successfully, but can’t visit web pages through browsers; then we know the issue lies with “host names not resolving”.

I would capture the DNS traffic and find out where it’s getting dropped. Then check the ACL to see if DNS traffic is allowed on port 53. Cheers!

[NunoFlora · Accepted solution]

I still don't know what the problem is but changed dns to 1.1.1.1 and solved all the dns problems

[MerryAki]

Or try preselecting Google or Cisco Umbrella DNS

But yes, cloudflare is performing better ✌️