TrueNAS Core 12.0-U8 -- Host name look-up failure

[MarioH]

I am using TrueNAS Core 12.0-U8 and experience a problem with DNS resolving:

I can ping any IP from the shell such as e.g. 142.251.25.206, but when trying to ping e.g. google.com (the IP-adress above) I receive the message "Host name look-up failure".

What I have tried so far:
- Used various name servers and inserted them in the Web GUI under Network/Global Configuration. Checked /etc/resolve.conf - the respective name servers were saved correctly in the file.
- Deleted the name server sentries in the Web GUI and manually added various name servers in /etc/resolve.conf (a proposal found in another thread).
- Checked DNS resolving with another Windows-PC in the same domain - everything worked as expected.

Any ideas or comments highly welcome - thanks in advance.

 

[Nick2253]

Can you post your /etc/resolv.conf

 

[MarioH]

Hi Nick,

this is the resolv.conf:

As said before, this were only some of the nameservers elaborated, furthermore a direct to 8.8.8.8 does not reveal any issues, so they are available and reachable for the server.

 

[Chris Moore]

Any ideas or comments highly welcome - thanks in advance.

Is the source of your ping the TrueNAS system or some kind of virtual machine running inside the TrueNAS?

 

[MarioH]

I try to ping from the CLI within TrueNAS, no virtual machine.

 

[Nick2253]

Let's try a couple troubleshooting steps (from the TrueNAS command line, post the output from each):

1. ping 8.8.8.8
2. dig www.google.com
3. dig @8.8.8.8 www.google.com

 

[MarioH]

Here we go:

1.

2.

3.

BTW: I enjoyed regarding "The Math on Hard Drive Failure"

 

[Nick2253]

Ok, so it looks like something weird is going on. If I didn't know any better, I'd guess that a firewall is blocking traffic via port 53.

To rule out a network issue, do you have any other DNS servers on your network that we can test? You mentioned that you were able to DNS lookups from your Windows PC to 8.8.8.8; did you use nslookup for that, or a different tool?

 

[MarioH]

I just checked for the sake of completeness: No, DNS (port 53) is not blocked by the firewall...

 

[MarioH]

And I checked on the Windows PC:

 

[Nick2253]

From the Windows PC, run: nslookup www.google.com 8.8.8.8

 

[MarioH]

Now it gets interesting:

 

[Patrick M. Hausen]

Firewall/ISP blocking DNS requests unless they use a local recursive server? What DNS server does your Windows system use (ipconfig /all)? Why don't you configure this one for your TrueNAS, too?

 

[MarioH]

No blocking from FW/ ISP (as far as I understand )
The DNS-Server for Windows and TrueNAS are the very same.

 

[MarioH]

Could it be that TrueNAS is "confused" because I did not set-up an IP-v6 Gateway?

 

[Patrick M. Hausen]

Is the DNS server an IPv6 address?

 

[MarioH]

No, everything is set-up in IP v4

 

[Patrick M. Hausen]

Netmask wrong by accident? So default gateway is outside of assumed local net and name server cannot be reached? Please post your global settings and your interface settings - anything else is not going to solve this.

 

[Nick2253]

The simple answer is that you need to determine what DNS server is set on your Windows PC, and use that on TrueNAS.

 

[MarioH]

You are asolutely right and I have tried exactly this before I posted the thread.

However, as is turns out more and more that it is rather an issue in the network-setup than with TrueNAS (thanks to Patrick for asking the right questions...) I will first solve this and in case the problem with TrueNAS persists I will come back to this community.

In the meantime many thanks to you all for your patience and the efforts!