Score:0

Can ping a DNS server, but cannot resolve hostname

jp flag

My Ubuntu 20.04 computer cannot browse any website. This only happens when connected to eduroam WIFI.

ping 8.8.8.8 works, but host google.com 8.8.8.8 says

Connection timed out; no servers could be reached.

I am not an expert on computer networks, could anyone tell me what is the next step in troubleshooting?

au flag
I'm not very familiar with eduroam, but I think it require you to use its DNS server (rather than a generic public server like 8.8.8.8).
ru flag
eduroam typically requires you to use their DNS servers. Also, keep in mind that `ping` and DNS use completely different protocols and methods of communication at the network level, so it's not unusual to see some networks block access to unauthorized DNS services - talk to your helpdesk for assistance.
Eric Power avatar
ng flag
Try the `dig` command (eg. `dig google.com`) and post the output?
Ge Zhang avatar
jp flag
`dig` produces no output for several seconds, and then say ; <<>> DiG 9.16.1-Ubuntu <<>> google.com ;; global options: +cmd ;; connection timed out; no servers could be reached
Aaron Wild avatar
kr flag
If you need to find the DNS server of your uni but can't contact the IT support for some reason -- here's a trick: Try connecting on your phone, and let it display which dns server it's using (this even works on iphone).
Score:2
cn flag

The next step in troubleshooting is to contact the eduroam WIFI helpdesk and ask them whether they are blocking DNS requests to external resolvers, and which DNS resolver you are supposed to use while on their network.

Rationale: It is quite common for educational institutions to limit the acceptable use of their network and to enforce this on the DNS level. In order to enforce this, they need to force their users to go through their DNS server for name resolution.

Ge Zhang avatar
jp flag
I seem to have a different problem. I brought another Windows 10 laptop, and this one works fine on eduroam. Using Windows subsystem for Linux, I was able to run `host google.com 8.8.8.8` without problem. I could also find the IPv4 DNS server on the windows laptop, "144.214.2.32", and if I run `host google.com 144.214.2.32` on my Linux computer, it too fails.
Tilman avatar
cn flag
So what did the helpdesk say?
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