[SOLVED] Help with ERR_NAME_NOT_RESOLVED

[Coulomb]

I've ran sudo apt-get update && upgrade, after rebooting, I am unable to access most of the websites.

ERR_NAME_NOT_RESOLVED is the error message I get. I can't google the error and try to fix it by trying things as the sites won't open.

Google itself does work. From the snippets I could figure out that it must have something to do with DNS settings. What caused it and what setting got messed up?

[Head_on_a_Stick]

Please post the output of

Code: Select all

apt policy
ip a
ip r
cat /etc/resolv.conf
ls -l /etc/resolv.conf
ping -c3 8.8.8.8
ping -c3 google.com
systemctl list-unit-files --state=enabled

Be sure to use code tags when posting the output, thanks.

[Coulomb]

Please post the output of

Code: Select all

apt policy
ip a
ip r
cat /etc/resolv.conf
ls -l /etc/resolv.conf
ping -c3 8.8.8.8
ping -c3 google.com
systemctl list-unit-files --state=enabled

Be sure to use code tags when posting the output, thanks.

Thank you for your reply, and sorry I missed it two days ago

Maybe it is worth mentioning that I got a new Router. I'm on Ethernet and no other device seems to have been impacted by it.

Code: Select all

phil@debian:~$ apt policy
Package files:
 100 /var/lib/dpkg/status
     release a=now
 500 http://download.opensuse.org/repositories/home:/stevenpusser:/new-hardware-support-buster/Debian_10  Packages
     release o=obs://build.opensuse.org/home:stevenpusser:new-hardware-support-buster/Debian_10,n=Debian_10,l=home:stevenpusser:new-hardware-support-buster,c=
     origin download.opensuse.org
 500 http://dl.google.com/linux/chrome/deb stable/main amd64 Packages
     release v=1.0,o=Google LLC,a=stable,n=stable,l=Google,c=main,b=amd64
     origin dl.google.com
 500 https://packagecloud.io/AtomEditor/atom/any any/main amd64 Packages
     release v=1,o=packagecloud.io/AtomEditor/atom,a=any,n=any,l=atom,c=main,b=amd64
     origin packagecloud.io
 500 http://deb.debian.org/debian buster-updates/main i386 Packages
     release o=Debian,a=stable-updates,n=buster-updates,l=Debian,c=main,b=i386
     origin deb.debian.org
 500 http://deb.debian.org/debian buster-updates/main amd64 Packages
     release o=Debian,a=stable-updates,n=buster-updates,l=Debian,c=main,b=amd64
     origin deb.debian.org
 500 http://http.us.debian.org/debian stable/non-free i386 Packages
     release v=10.3,o=Debian,a=stable,n=buster,l=Debian,c=non-free,b=i386
     origin http.us.debian.org
 500 http://http.us.debian.org/debian stable/non-free amd64 Packages
     release v=10.3,o=Debian,a=stable,n=buster,l=Debian,c=non-free,b=amd64
     origin http.us.debian.org
 500 http://http.us.debian.org/debian stable/contrib i386 Packages
     release v=10.3,o=Debian,a=stable,n=buster,l=Debian,c=contrib,b=i386
     origin http.us.debian.org
 500 http://http.us.debian.org/debian stable/contrib amd64 Packages
     release v=10.3,o=Debian,a=stable,n=buster,l=Debian,c=contrib,b=amd64
     origin http.us.debian.org
 500 http://http.us.debian.org/debian stable/main i386 Packages
     release v=10.3,o=Debian,a=stable,n=buster,l=Debian,c=main,b=i386
     origin http.us.debian.org
 500 http://http.us.debian.org/debian stable/main amd64 Packages
     release v=10.3,o=Debian,a=stable,n=buster,l=Debian,c=main,b=amd64
     origin http.us.debian.org
 100 http://deb.debian.org/debian buster-backports/main i386 Packages
     release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=main,b=i386
     origin deb.debian.org
 100 http://deb.debian.org/debian buster-backports/main amd64 Packages
     release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=main,b=amd64
     origin deb.debian.org
 500 http://security.debian.org/debian-security buster/updates/main i386 Packages
     release v=10,o=Debian,a=stable,n=buster,l=Debian-Security,c=main,b=i386
     origin security.debian.org
 500 http://security.debian.org/debian-security buster/updates/main amd64 Packages
     release v=10,o=Debian,a=stable,n=buster,l=Debian-Security,c=main,b=amd64
     origin security.debian.org
 500 http://deb.debian.org/debian buster/main i386 Packages
     release v=10.3,o=Debian,a=stable,n=buster,l=Debian,c=main,b=i386
     origin deb.debian.org
 500 http://deb.debian.org/debian buster/main amd64 Packages
     release v=10.3,o=Debian,a=stable,n=buster,l=Debian,c=main,b=amd64
     origin deb.debian.org
Pinned packages:
phil@debian:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 0c:9d:92:c2:d7:5e brd ff:ff:ff:ff:ff:ff
    inet6 2003:e3:2f27:fc16:b174:775e:9015:c08e/64 scope global temporary dynamic 
       valid_lft 604292sec preferred_lft 85715sec
    inet6 2003:e3:2f27:fc16:e9d:92ff:fec2:d75e/64 scope global dynamic mngtmpaddr noprefixroute 
       valid_lft 604784sec preferred_lft 86384sec
    inet6 fe80::e9d:92ff:fec2:d75e/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
phil@debian:~$ ip r
phil@debian:~$ cat /etc/resolv.conf
# Generated by NetworkManager
nameserver fe80::1%eno1
phil@debian:~$ ls -l /etc/resolv.conf
-rw-r--r-- 1 root root 54 Feb 29 11:51 /etc/resolv.conf
phil@debian:~$ ping -c3 8.8.8.8
connect: Network is unreachable
phil@debian:~$ ping -c3 google.com
PING google.com(fra16s24-in-x0e.1e100.net (2a00:1450:4001:824::200e)) 56 data bytes
64 bytes from fra16s24-in-x0e.1e100.net (2a00:1450:4001:824::200e): icmp_seq=1 ttl=57 time=23.8 ms
64 bytes from fra16s24-in-x0e.1e100.net (2a00:1450:4001:824::200e): icmp_seq=2 ttl=57 time=23.7 ms
64 bytes from fra16s24-in-x0e.1e100.net (2a00:1450:4001:824::200e): icmp_seq=3 ttl=57 time=23.6 ms

--- google.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 5ms
rtt min/avg/max/mdev = 23.555/23.693/23.804/0.103 ms
phil@debian:~$ systemctl list-unit-files --state-=enabled
systemctl: unrecognized option '--state-=enabled'
phil@debian:~$ sudo systemctl list-unit-files --state-=enabled
[sudo] password for phil: 
systemctl: unrecognized option '--state-=enabled'
phil@debian:~$ 

[Head_on_a_Stick]

Code: Select all

 500 http://download.opensuse.org/repositories/home:/stevenpusser:/new-hardware-support-buster/Debian_10  Packages

What did you install from Steve's repository?

Code: Select all

aptitude search '?narrow(?installed, ?origin(obs))'

And you shouldn't mix release names ("buster") and archives ("stable") because they won't match when bullseye becomes the new stable version. Pick one and use it universally in your sources. That's incidental to your current problem though.

Code: Select all

phil@debian:~$ ip r

You have no routes defined. That command should list your gateway (router) address.

Code: Select all

phil@debian:~$ cat /etc/resolv.conf
# Generated by NetworkManager
nameserver fe80::1%eno1

I don't think that's a valid address. But I don't use IPv6 so I may be wrong. Wait for somebody who does use it, they might be able to advise better.

The ping outputs certainly seem to show an incorrect nameserver.

NetworkManager is overkill for a basic ethernet connection and it seems to be messing things up for you. As a temporary fix try this:

Code: Select all

# systemctl stop network-manager NetworkManager{,-dispatcher,-wait-online}
# dhclient eno1
# tee /etc/resolv.conf <<<"nameserver 2620:fe::fe"

Does that work?

Code: Select all

phil@debian:~$ systemctl list-unit-files --state-=enabled

That's not the command I posted, use copy&paste on my code block to avoid transcription errors.

[Coulomb]

Ok, so while writing my response and trying your tips, the problem disappeared. Unfortunately, I don't know what was successful in the end. But maybe by telling you what I did you can tell me and so I know for future reference:

I unplugged my network cable and
deleted all the connection-settings,
plugged in a misho MacBook Ethernet to USB Adapter, then I
disabled ipv6 since it may have been causing issues.

I then unplugged the Ethernet to USB and
replugged the network Cable into the Ethernet port on the Motherboard.

Everything works fine now, the output of ip r is now:

Code: Select all

phil@debian:~$ ip r
default via 192.168.2.1 dev eno1 proto dhcp metric 100 
169.254.0.0/16 dev eno1 scope link metric 1000 
192.168.2.0/24 dev eno1 proto kernel scope link src 192.168.2.106 metric 10

Code: Select all

 500 http://download.opensuse.org/repositories/home:/stevenpusser:/new-hardware-support-buster/Debian_10  Packages

What did you install from Steve's repository?

I use(d) the nVidia graphics card driver from that repo.

The ping outputs certainly seem to show an incorrect nameserver.

Now the ping of 8.8.8.8 is:

Code: Select all

phil@debian:~$ ping -c3 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=57 time=20.9 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=57 time=21.3 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=57 time=28.2 ms

--- 8.8.8.8 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 5ms
rtt min/avg/max/mdev = 20.944/23.468/28.178/3.335 ms

And you shouldn't mix release names ("buster") and archives ("stable") because they won't match when bullseye becomes the new stable version. Pick one and use it universally in your sources. That's incidental to your current problem though.

What should I delete in my sources? I'm don't 100% understand what you mean

Code: Select all

phil@debian:~$ grep -v '^#\|^$' /etc/apt/sources.list{,.d/*}
/etc/apt/sources.list:deb http://deb.debian.org/debian/ buster main 
/etc/apt/sources.list:deb-src http://deb.debian.org/debian/ buster main 
/etc/apt/sources.list:deb http://security.debian.org/debian-security/ buster/updates main 
/etc/apt/sources.list:deb-src http://security.debian.org/debian-security/ buster/updates main 
/etc/apt/sources.list:deb http://deb.debian.org/debian/ buster-backports main 
/etc/apt/sources.list:deb http://http.us.debian.org/debian/ stable main contrib non-free 
/etc/apt/sources.list:deb http://deb.debian.org/debian/ buster-updates main 
/etc/apt/sources.list:deb-src http://deb.debian.org/debian/ buster-updates main   
/etc/apt/sources.list.d/atom.list:deb [arch=amd64] https://packagecloud.io/AtomEditor/atom/any/ any main
/etc/apt/sources.list.d/google-chrome.list:deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main 
/etc/apt/sources.list.d/home:stevenpusser:new-hardware-support-buster.list:deb http://download.opensuse.org/repositories/home:/stevenpusser:/new-hardware-support-buster/Debian_10/ /

[Head_on_a_Stick]

disabled ipv6 since it may have been causing issues

Yes, I probably should have suggested that. Good call.

What should I delete in my sources?

Please replace that oversized image with a plain URL to help forum users with limited bandwidth, thanks.

This will show your sources in plain text:

Code: Select all

grep -v '^#\|^$' /etc/apt/sources.list{,.d/*}

You should remove the http.us.debian.org line (which declares "stable" instead of "buster") and add the contrib & non-free components to the deb lines for deb.debian.org for both buster and buster-updates. There's no need to add an extra source just for those components.

See also https://wiki.debian.org/SourcesList#Exa ... urces.list

[Coulomb]

Please replace that oversized image with a plain URL to help forum users with limited bandwidth, thanks.

Yes, I am aware, I wanted to use BBCode [img=250x250]url[/img] but the forum doesn't support it.

See also https://wiki.debian.org/SourcesList#Exa ... urces.list

Thank you very much for assisting

[Coulomb]

disabled ipv6 since it may have been causing issues

Yes, I probably should have suggested that. Good call.

Now, I just disabled IPv6 in network connections as well as used these commands:

Code: Select all

 sysctl -w net.ipv6.conf.all.disable_ipv6=1
sysctl -w net.ipv6.conf.default.disable_ipv6=

but clicking on network I still am shown an IPV6 address as well as visiting webistes like https://test-ipv6.com/ i have an IPV6 address.
Why did disabling it not suffice?

EDIT:

After editing and edding these lines and rebooting, IPV6 address is disabled.

Code: Select all

 /etc/sysctl.d/99-sysctl.conf
 
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

However, now the Network manager takes about 15 seconds to Wait Online. Probably a good idea to disable it after all.

[p.H]

Code: Select all

phil@debian:~$ ip a
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 0c:9d:92:c2:d7:5e brd ff:ff:ff:ff:ff:ff
    inet6 2003:e3:2f27:fc16:b174:775e:9015:c08e/64 scope global temporary dynamic
       valid_lft 604292sec preferred_lft 85715sec
    inet6 2003:e3:2f27:fc16:e9d:92ff:fec2:d75e/64 scope global dynamic mngtmpaddr noprefixroute
       valid_lft 604784sec preferred_lft 86384sec
    inet6 fe80::e9d:92ff:fec2:d75e/64 scope link noprefixroute
       valid_lft forever preferred_lft forever
phil@debian:~$ ip r
phil@debian:~$ cat /etc/resolv.conf
# Generated by NetworkManager
nameserver fe80::1%eno1

Total lack of IPv4 configuration. Maybe the DHCP negotiation failed. Global IPv6 configuration looks fine.
Google is reachable because it is available with both IPv4 and IPv6. Websites such as this forum which are available only with IPv4 are unreachable.

You have no routes defined.

No IPv4 routes. I bet that

Code: Select all

ip -6 route

would have shown correct IPv6 routes.

That command should list your gateway (router) address.

You mean the default route. It should have listed the local subnet direct route too.

Code: Select all

nameserver fe80::1%eno1

I don't think that's a valid address.

It is a valid address : a link local address suffixed by the interface connected to the local network, making it a fully qualified unicast address.

The ping outputs certainly seem to show an incorrect nameserver.

How can you say that ? The nameserver resolves google.com correctly and ping works fine (using IPv6).

disabled ipv6 since it may have been causing issues

Yes, I probably should have suggested that.

Please guys. Disabling IPv6 helps only with a broken IPv6 configuration, not when the IPv4 configuration is broken. Here the IPv6 configuration works fine.

[Head_on_a_Stick]

The ping outputs certainly seem to show an incorrect nameserver.

How can you say that ?

I misread the output, sorry OP.

Thanks for the clarifications p.H

[Coulomb]

Please guys. Disabling IPv6 helps only with a broken IPv6 configuration, not when the IPv4 configuration is broken. Here the IPv6 configuration works fine.

I usually have ipv6 disabled. My VPN disables it anyway. But like I wrote in previous post, the problem "solved" itself after I have connected using a ethernet to usb adapter and reconnected using my regular ethernet port.

Google is reachable because it is available with both IPv4 and IPv6. Websites such as this forum which are available only with IPv4 are unreachable.

That's good information