Strange DNS behaviour

[Xavier Humbert]

Hi,

My DNS system if perfectly working :

> [xavier at numenor ~]$ dig dns.google.com
>
> ; <<>> DiG 9.16.15 <<>> dns.google.com
> ;; global options: +cmd
> ;; Got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12276
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
>
> ;; OPT PSEUDOSECTION:
> ; EDNS: version: 0, flags:; udp: 1232
> ; COOKIE: 7b606d7c32a99906010000006097b6d7f61894ea0a92dac2 (good)
> ;; QUESTION SECTION:
> ;dns.google.com.                        
> IN      A
>
> ;; ANSWER SECTION:
> dns.google.com.         880     IN      A       
> 8.8.4.4
> dns.google.com.         880     IN      A       
> 8.8.8.8
>
> ;; Query time: 0 msec
> ;; SERVER: ::1#53(::1)
> ;; WHEN: Sun May 09 12:17:59 CEST 2021
> ;; MSG SIZE  rcvd: 103

On other hosts in my home, it works, too.

But on one machine, it fails :

> [xavier at feanor ~]$ dig @numenor dns.google.com +trace
>
> ; <<>> DiG 9.16.8-Ubuntu <<>> @numenor dns.google.com +trace
> ; (1 server found)
> ;; global options: +cmd
> .                       518400  IN      NS 
>      m.root-servers.net.
> .                       518400  IN      NS 
>      b.root-servers.net.
> .                       518400  IN      NS 
>      e.root-servers.net.
> .                       518400  IN      NS 
>      d.root-servers.net.
> .                       518400  IN      NS 
>      h.root-servers.net.
> .                       518400  IN      NS 
>      f.root-servers.net.
> .                       518400  IN      NS 
>      g.root-servers.net.
> .                       518400  IN      NS 
>      c.root-servers.net.
> .                       518400  IN      NS 
>      i.root-servers.net.
> .                       518400  IN      NS 
>      j.root-servers.net.
> .                       518400  IN      NS 
>      k.root-servers.net.
> .                       518400  IN      NS 
>      l.root-servers.net.
> .                       518400  IN      NS 
>      a.root-servers.net.
> .                       518400  IN 
>      RRSIG   NS 8 0 518400 20210521170000 20210508160000 14631 
> . IgUiqHrRXT5hTAa5wnubyCL0T9iq+iRAQIUQlIStRYqZh6Qp5W3sZLum 
> 6O+EkYZALJda6RJwQY8oPEgQVQymGmGyAxcZBekX5vsMm8MgovQIA+Ev 
> SroSeV9yXDURHqt8af+25bw
> 6YyUQEOblPehxyUYYkF9cP8FlieAUw1Fn 
> HMvqpQlEn2sYS4UjA+euhcS2k7jnyEdBNbXbEZVq56zHK1aHPQIp2f4/ 
> byHaC55zPJ5rgLwMUh+8JuP47wb4NWAKIj76EUlqcidfI8hxZI5KPoNZ 
> vmIcEtQSfRYqVxoc+BiEEgalw5afAmXjEtvJaWm4v5383uatiQ1s9AgC MPQFHw==
> couldn't get address for 'm.root-servers.net': not found

None of the root servers can't be found. My root hint file is up to date.

The network configuration on this machine :

> [xavier at feanor ~]$ nmcli device show enp10s0
> GENERAL.DEVICE:                         enp10s0
> GENERAL.TYPE: 
>                           ethernet
> GENERAL.HWADDR: 
>                         04:7D:7B:02:68:67
> GENERAL.MTU:                            1500
> GENERAL.STATE:                          100 
> (connected)
> GENERAL.CONNECTION:                     Wired
> GENERAL.CON-PATH: 
>                       /org/freedesktop/NetworkManager/ActiveConnection/3 
>
> WIRED-PROPERTIES.CARRIER:               on
> IP4.ADDRESS[1]: 
>                         192.168.100.25/24
> IP4.GATEWAY: 
>                            192.168.100.254
> IP4.ROUTE[1]:                           dst 
> = 0.0.0.0/0, nh = 192.168.100.254, mt = 100
> IP4.ROUTE[2]:                           dst 
> = 192.168.100.0/24, nh = 0.0.0.0, mt = 100
> IP4.ROUTE[3]:                           dst 
> = 169.254.0.0/16, nh = 0.0.0.0, mt = 1000
> IP4.DNS[1]: 
>                             192.168.100.144
> IP4.DNS[2]: 
>                             192.168.100.254
This is not an ACL problem, the whole subnet is allowed. Nmap and/or 
telnet shows no blocked port problem

Trying on the secondary leads to the same behaviour

Eventually, I am lost.

Could anyone help ?

Thanks,

Regards

-- 
Xavier Humbert
CRT Supervision et Exploitation de Niveau 1
Rectorat de Nancy-Metz
03 83 86 27 39

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