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I am suddenly having a problem running updates on an Ubuntu 18.04.5 server after years of running weekly updates without any problems. It seems to be DNS related.

I am able to ping outside IP addresses but not FQDNs. I am able to connect to this machine from outside the network with SSH, so I know the connection is working.

systemd-resolve --status shows:

> Global
>          DNS Servers: 1.1.1.1
>                       1.0.0.1
>                       8.8.8.8
>           DNSSEC NTA: 10.in-addr.arpa
>                       16.172.in-addr.arpa
>                       168.192.in-addr.arpa
>                       17.172.in-addr.arpa
>                       18.172.in-addr.arpa
>                       19.172.in-addr.arpa
>                       20.172.in-addr.arpa
>                       21.172.in-addr.arpa
>                       22.172.in-addr.arpa
>                       23.172.in-addr.arpa
>                       24.172.in-addr.arpa
>                       25.172.in-addr.arpa
>                       26.172.in-addr.arpa
>                       27.172.in-addr.arpa
>                       28.172.in-addr.arpa
>                       29.172.in-addr.arpa
>                       30.172.in-addr.arpa
>                       31.172.in-addr.arpa
>                       corp
>                       d.f.ip6.arpa
>                       home
>                       internal
>                       intranet
>                       lan
>                       local
>                       private
>                       test
> 
> Link 2 (eth0)
>       Current Scopes: none
>        LLMNR setting: yes MulticastDNS setting: no
>       DNSSEC setting: no
>     DNSSEC supported: no

I am stumped and would appreciate any assistance.

  • What is the content of the /etc/resolv.conf file? – Michael Hampton Oct 28 at 21:24
  • nameserver 1.1.1.1 nameserver 1.0.0.1 nameserver 8.8.8.8 – Vonnegut Oct 28 at 21:31
  • Seems reasonable. So what happens if you try to ping a FQDN? – Michael Hampton Oct 28 at 21:33
  • a good long delay of about 20 seconds and then ping: yahoo.com: Temporary failure in name resolution – Vonnegut Oct 28 at 21:34
  • Check your network connectivity and firewalls. – Michael Hampton Oct 28 at 21:56
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Server settings ended up being fine. The network team made changes to Cisco Umbrella without informing me. Changed nameservers to the Umbrella DNS servers and it is working now.

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