Random DNS problem on Tumbleweed

English Network/Internet
1

Hi guys I need some help I have random network problems I think DNS related.

Randomly my DNS is not working, I have ruled out the problem with the router because DNS works on Android via wifi.

This is what I get when DNS stop working.

kristijan-> ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.710 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.610 ms

--- 192.168.1.1 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1011ms
rtt min/avg/max/mdev = 0.610/0.660/0.710/0.050 ms

~]
[14:06]
kristijan-> nslookup 192.168.1.1
;; connection timed out; no servers could be reached

~]
[14:06]
kristijan-> resolvectl
Global
           Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=allow-downgrade/unsupported
    resolv.conf mode: foreign
  Current DNS Server: 192.168.1.1
         DNS Servers: 192.168.1.1 4.4.4.4 1.1.1.1
Fallback DNS Servers: 1.1.1.1#cloudflare-dns.com 8.8.8.8#dns.google 1.0.0.1#cloudflare-dns.com 8.8.4.4#dns.google
                      2606:4700:4700::1111#cloudflare-dns.com 2001:4860:4860::8888#dns.google
                      2606:4700:4700::1001#cloudflare-dns.com 2001:4860:4860::8844#dns.google

Link 2 (eno1)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=allow-downgrade/unsupported
Current DNS Server: 192.168.1.1
       DNS Servers: 192.168.1.1 4.4.4.4 1.1.1.1

Link 3 (anbox0)
Current Scopes: none
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=allow-downgrade/supported


kristijan-> networkctl
IDX LINK   TYPE     OPERATIONAL SETUP    
  1 lo     loopback carrier     unmanaged
  2 eno1   ether    routable    unmanaged
  3 anbox0 bridge   no-carrier  unmanaged

3 links listed.

kristijan-> cat /etc/resolv.conf
### /etc/resolv.conf is a symlink to /var/run/netconfig/resolv.conf
### autogenerated by netconfig!
#
# Before you change this file manually, consider to define the
# static DNS configuration using the following variables in the
# /etc/sysconfig/network/config file:
#     NETCONFIG_DNS_STATIC_SEARCHLIST
#     NETCONFIG_DNS_STATIC_SERVERS
#     NETCONFIG_DNS_FORWARDER
# or disable DNS configuration updates via netconfig by setting:
#     NETCONFIG_DNS_POLICY=''
#
# See also the netconfig(8) manual page and other documentation.
#
### Call "netconfig update -f" to force adjusting of /etc/resolv.conf.
nameserver 192.168.1.1
nameserver 4.4.4.4
nameserver 1.1.1.1

This is after I do network disable/enable in Network Manager

kristijan-> nslookup 192.168.1.1
1.1.168.192.in-addr.arpa        name = router.lan.

Authoritative answers can be found from:
router.lan      internet address = 192.168.1.1
2

When you run into the problem can you try “dig forums.opensuse.org @192.168.1.1”

3

Thank you for replay. I did not get mail notification about your replay.
This was my first post so i have to change default settings of Default Thread Subscription Mode to receive instant mail notification.

Problem persist. But it is really random, for 10 days everything works without problem and than one day every 5-10min i lose DNS.

kristijan-> dig forums.opensuse.org @192.168.1.1 

; <<>> DiG 9.16.25 <<>> forums.opensuse.org @192.168.1.1 
;; global options: +cmd 
;; connection timed out; no servers could be reached


kristijan-> ping 192.168.1.1 
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 
64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=0.659 ms 
64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=28.4 ms 

--- 192.168.1.1 ping statistics --- 
2 packets transmitted, 2 received, 0% packet loss, time 1031ms 
rtt min/avg/max/mdev = 0.659/14.523/28.388/13.864 ms 

kristijan-> ping 4.4.4.4
PING 4.4.4.4 (4.4.4.4) 56(84) bytes of data. 
^C 
--- 4.4.4.4 ping statistics --- 
2 packets transmitted, 0 received, 100% packet loss, time 1007ms


kristijan-> 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 
2: **eno1: **<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state **UP **group default qlen 1000 
    link/ether **38:2c:4a:b5:a4:e6** brd **ff:ff:ff:ff:ff:ff**
    altname enp0s25 
    inet **192.168.1.5**/24 brd **192.168.1.255 **scope global dynamic noprefixroute eno1 
       valid_lft 495sec preferred_lft 495sec 
    inet6 **fe80::6130:dc2c:2d69:4c28**/64 scope link noprefixroute  
       valid_lft forever preferred_lft forever 
3: **anbox0: **<NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state **DOWN **group default qlen 1000 
    link/ether **3a:79:2b:5e:ee:a6** brd **ff:ff:ff:ff:ff:ff**
    inet **192.168.250.1**/24 scope global anbox0 
       valid_lft forever preferred_lft foreve


kristijan-> resolvectl
**Global**
       Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported 
resolv.conf mode: foreign 

**Link 2 (eno1)**
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6 
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported 
Current DNS Server: 1.1.1.1 
       DNS Servers: 1.1.1.1 

**Link 3 (anbox0)**
Current Scopes: none 
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported



kristijan-> networkctl
IDX LINK   TYPE     OPERATIONAL SETUP    
  1 lo     loopback **carrier    ** unmanaged 
  2 eno1   ether    **routable   ** unmanaged 
  3 anbox0 bridge   no-carrier  unmanaged 

3 links listed.


kristijan-> ip route
default via **192.168.1.1 **dev **eno1 **proto dhcp metric 20100  
**192.168.1.0/24 **dev **eno1 **proto kernel scope link src **192.168.1.5 **metric 100  
**192.168.250.0/24 **dev **anbox0 **proto kernel scope link src **192.168.250.1 **linkdown
4

Does

dig @8.8.8.8 forums.opensuse.org

work at this point?

Install wireshark and when this happens again run

dumpcap -s 1500 -i eno1 -w /tmp/dig.pcapng
dig forums.opensuse.org @192.168.1.1

and make /tmp/dig.pcapng available (unfortunately, susepaste does not support uploading of arbitrary binary files).

kristijan-> resolvectl

You are not using systemd-resolved, so this is likely irrelevant. It would be interesting to test if stopping systemd-resolved changes anything,

P.S. and please​ do not use colors when posting computer text. I can hardly read some words (actually I cannot, I can only guess what they are).

5

Default configuration of DNS is the biggest annoyance to my experience. I switched host Leap-15-3 to NetworkManager / systemd-resolved.
:

**Leap-15-3:~ #** resolvectl  
**Global**
       Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported 
resolv.conf mode: uplink                                         

**Link 2 (eth0)**
Current Scopes: none                                                         
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported 

**Link 3 (wlan0)**
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6                                    
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported 
Current DNS Server: fd00:XXXXXXXXXXXX....                                    
       DNS Servers: fd00:XXXXXXXXXXXX.... 192.168.178.1                       
        DNS Domain: fritz.box ~.                                                 
**Leap-15-3:~ #**

[FONT=monospace]**Leap-15-3:~ #** systemctl status systemd-resolved.service  
**●** systemd-resolved.service - Network Name Resolution 
     Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: disabled) 
     Active: **active (running)** since Fri 2022-03-04 06:57:36 CET; 17min ago 
       Docs: man:systemd-resolved.service(8) 
             https://www.freedesktop.org/wiki/Software/systemd/resolved 
             https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers 
             https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients 
   Main PID: 513 (systemd-resolve) 
     Status: "Processing requests..." 
      Tasks: 1 (limit: 4915) 
     CGroup: /system.slice/systemd-resolved.service 
             └─513 /usr/lib/systemd/systemd-resolved 

Mar 04 06:57:36 Leap-15-3 systemd[1]: Starting Network Name Resolution... 
Mar 04 06:57:36 Leap-15-3 systemd-resolved[513]: Positive Trust Anchors: 
Mar 04 06:57:36 Leap-15-3 systemd-resolved[513]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d 
Mar 04 06:57:36 Leap-15-3 systemd-resolved[513]: Negative trust anchors: home.arpa 10.in-addr.arpa 16.172.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-a>
Mar 04 06:57:36 Leap-15-3 systemd-resolved[513]: Using system hostname 'Leap-15-3'. 
Mar 04 06:57:36 Leap-15-3 systemd[1]: Started Network Name Resolution. 
**Leap-15-3:~ #**[/FONT]

https://en.opensuse.org/Network_Management_With_Systemd#Disable_Changes_To_DNS_Through_Netconfig
https://en.opensuse.org/Network_Management_With_Systemd#Enable_Network_Name_Resolution

6 
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
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 38:2c:4a:b5:a4:e6 brd ff:ff:ff:ff:ff:ff
    altname enp0s25
    inet 192.168.1.5/24 brd 192.168.1.255 scope global noprefixroute eno1
       valid_lft forever preferred_lft forever
    inet6 fe80::4577:489d:6879:7c74/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: anbox0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 3a:79:2b:5e:ee:a6 brd ff:ff:ff:ff:ff:ff
    inet 192.168.250.1/24 scope global anbox0
       valid_lft forever preferred_lft forever


kristijan-> dig forums.opensuse.org @192.168.1.1

; <<>> DiG 9.16.25 <<>> forums.opensuse.org @192.168.1.1
;; global options: +cmd
;; connection timed out; no servers could be reached

~]
[21:37]
kristijan-> dig @8.8.8.8 forums.opensuse.org

; <<>> DiG 9.16.25 <<>> @8.8.8.8 forums.opensuse.org
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached

dig.pcapng
https://www.dropbox.com/s/yyec09tw49fsejv/dig.pcapng?dl=0

kristijan-> systemctl status systemd-resolved.service 
● systemd-resolved.service - Network Name Resolution
     Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: disabled)
     Active: active (running) since Fri 2022-03-11 11:07:51 CET; 11h ago
       Docs: man:systemd-resolved.service(8)
             man:org.freedesktop.resolve1(5)
             https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers
             https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients
   Main PID: 1364 (systemd-resolve)
     Status: "Processing requests..."
      Tasks: 1 (limit: 4915)
        CPU: 211ms
     CGroup: /system.slice/systemd-resolved.service
             └─1364 /usr/lib/systemd/systemd-resolved

Mar 11 21:52:25 homePC systemd-resolved[1364]: eno1: Bus client set default route setting: no
Mar 11 21:52:25 homePC systemd-resolved[1364]: eno1: Bus client reset DNS server list.
Mar 11 21:52:33 homePC systemd-resolved[1364]: eno1: Bus client set default route setting: yes
Mar 11 21:52:33 homePC systemd-resolved[1364]: eno1: Bus client set DNS server list to: 192.168.1.1
Mar 11 21:52:47 homePC systemd-resolved[1364]: Using degraded feature set UDP instead of UDP+EDNS0 for DNS server 192.168.1.1.
Mar 11 21:59:18 homePC systemd-resolved[1364]: eno1: Bus client set default route setting: no

kristijan-> resolvectl status
Global
       Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: uplink

Link 2 (eno1)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 192.168.1.1
       DNS Servers: 192.168.1.1

Link 3 (anbox0)
Current Scopes: none
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
~/.local/share/servicemenu-download/124416-DropboxServiceMenu-0.16.1.tar.gz-dir/DropboxServiceMenu-0.16.1]
[21:56]
kristijan-> ll /etc/resolv.conf
lrwxrwxrwx 1 root root 32 Mar  6 18:00 /etc/resolv.conf -> /run/systemd/resolve/resolv.conf


kristijan-> cat /etc/resolv.conf
# This is /run/systemd/resolve/resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 192.168.1.1
search .

Thank you both on comments and help.
I am using NetworkManager and systemd-resolved.

7

The 192.168.1.1 does not run any resolver at all. Nothing listens on port 53

No.  Time           Source         SPort    Destination    DPort Protocol Length    Info
2    0.092089171    192.168.1.5    35400    192.168.1.1    53    DNS          78    Standard query 0x626f A api.dropboxapi.com
3    0.092095084    192.168.1.5    35400    192.168.1.1    53    DNS          78    Standard query 0x4b6c AAAA api.dropboxapi.com
4    0.092831428    192.168.1.1    35400    192.168.1.5    53    ICMP        106    Destination unreachable (Port unreachable)

I am using … systemd-resolved.

I already told you you do not. At least, no program that is using /etc/resolv.conf directly is using systemd-resolved. Show your /etc/nsswitch.conf to check whether systemd-resolved may be used.

You also seem to have some generic issue with port blocking because even attempt to ask Google DNS server 8.8.8.8 fails. You have some networking issues outside of your Tumbleweed system.

8
  1. Check your router (192.168.1.1) for proper DHCP / DNS. Refer to its documentation and configure properly.
  2. Network Management With Systemd - openSUSE Wiki is based on default /etc/nsswitch.conf Verify as follows:
**i3-4130:~ #** rpm -qf /etc/nsswitch.conf 
glibc-2.35-2.1.x86_64 
**i3-4130:~ #** rpm -V glibc                          
**i3-4130:~ #**
9

I did

systemctl stop systemd-resolved
systemctl disable systemd-resolved

DNS works for now i will have to wait

I have tried stopping systemd-resolved before but i lost DNS after that… maybe it was coincidence, bad timing cause i am losing DNS every few minutes…

kristijan-> cat /etc/nsswitch.conf  
#
# /etc/nsswitch.conf
#
# An example Name Service Switch config file. This file should be
# sorted with the most-used services at the beginning.
#
# Valid databases are: aliases, ethers, group, gshadow, hosts,
# initgroups, netgroup, networks, passwd, protocols, publickey,
# rpc, services, and shadow.
#
# Valid service provider entries include (in alphabetical order):
#
#       compat                  Use /etc files plus *_compat pseudo-db
#       db                      Use the pre-processed /var/db files
#       dns                     Use DNS (Domain Name Service)
#       files                   Use the local files in /etc
#       hesiod                  Use Hesiod (DNS) for user lookups
#       nis                     Use NIS (NIS version 2), also called YP
#       nisplus                 Use NIS+ (NIS version 3)
#
# See `info libc 'NSS Basics'` for more information.
#
# Commonly used alternative service providers (may need installation):
#
#       ldap                    Use LDAP directory server
#       myhostname              Use systemd host names
#       mymachines              Use systemd machine names
#       mdns*, mdns*_minimal    Use Avahi mDNS/DNS-SD
#       resolve                 Use systemd resolved resolver
#       sss                     Use System Security Services Daemon (sssd)
#       systemd                 Use systemd for dynamic user option
#       winbind                 Use Samba winbind support
#       wins                    Use Samba wins support
#       wrapper                 Use wrapper module for testing
#
# Notes:
#
# 'sssd' performs its own 'files'-based caching, so it should generally
# come before 'files'.
#
# WARNING: Running nscd with a secondary caching service like sssd may
#          lead to unexpected behaviour, especially with how long
#          entries are cached.
#
# Installation instructions:
#
# To use 'db', install the appropriate package(s) (provide 'makedb' and
# libnss_db.so.*), and place the 'db' in front of 'files' for entries
# you want to be looked up first in the databases, like this:
#
# passwd:    db files
# shadow:    db files
# group:     db files

passwd:         compat
group:          compat
shadow:         compat
# Allow initgroups to default to the setting for group.
# initgroups:   compat

hosts:          files mdns_minimal [NOTFOUND=return] dns
networks:       files dns

aliases:        files usrfiles
ethers:         files usrfiles
gshadow:        files usrfiles
netgroup:       files nis
protocols:      files usrfiles
publickey:      files
rpc:            files usrfiles
services:       files usrfiles

automount:      files nis
bootparams:     files
netmasks:       files

I also did

kristijan-> rpm -qf /etc/nsswitch.conf
glibc-2.35-2.1.x86_64
kristijan-> rpm -V glibc

I am using MikroTik RB2011 as router. When i lose DNS on PC i have it over WiFi so i don’t think it is router setup.
The router worked well and I haven’t messed with the config recently.
I would say that using systemd-resolved is cause of some kind of conflict.

But, will wait and see…

Thank you !

10

Any reason you installed systemd-resolved in the first place?

kristijan-> cat /etc/nsswitch.conf  
hosts:          files mdns_minimal [NOTFOUND=return] dns

Your system is not set to use systemd-resolved in any way (except some programs that explicitly contact it via D-Bus API).

11

Using systemd-resolved requires 2 changes. From Network Management With Systemd - openSUSE Wiki

  1. Disable Changes To DNS Through Netconfig
    Yast2 sysconfig may be used. Verify:
3400G:~ # grep NETCONFIG_DNS_POLICY /etc/sysconfig/network/config
NETCONFIG_DNS_POLICY=""
3400G:~ #
  1. Enable Network Name Resolution
    Resolve domain names, IPV4 and IPv6 addresses, DNS resource records, and services; introspect and reconfigure the DNS resolver
    Check current setting of /etc/resolve.conf:
erlangen:~ # ll /etc/resolv.conf
lrwxrwxrwx 1 root root 30 Nov 27 07:54 /etc/resolv.conf -> /var/run/netconfig/resolv.conf
erlangen:~ #

Save path and contents of target file (handy in case of undoing the changes).

Make sure /etc/resolve.conf is managed by resolved:

3400G:~ # ln -sf /run/systemd/resolve/resolv.conf /etc/
3400G:~ # systemctl enable --now systemd-resolved
3400G:~ #
12

As usual you do not understand what you are talking about. Your instructions result in bypassing systemd-resolved. The only program that will be using it is resolvectl.

13

It`s not working after reboot

homePC:/home/kristijan # systemctl status systemd-resolved
○ systemd-resolved.service - Network Name Resolution
     Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; disabled; vendor preset: disabled)
     Active: inactive (dead)
       Docs: man:systemd-resolved.service(8)
             man:org.freedesktop.resolve1(5)
             https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers
             https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients

homePC:/home/kristijan # resolvectl
Failed to get global data: Unit dbus-org.freedesktop.resolve1.service not found.

homePC:/home/kristijan # cat /etc/resolv.conf
cat: /etc/resolv.conf: No such file or directory

homePC:/home/kristijan # ip r
default via 192.168.1.1 dev eno1 proto static metric 20100
192.168.1.0/24 dev eno1 proto kernel scope link src 192.168.1.5 metric 100
192.168.250.0/24 dev anbox0 proto kernel scope link src 192.168.250.1 linkdown

homePC:/home/kristijan # dig @8.8.8.8 forums.opensuse.org

; <<>> DiG 9.16.25 <<>> @8.8.8.8 forums.opensuse.org
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35744
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;forums.opensuse.org.           IN      A

;; ANSWER SECTION:
forums.opensuse.org.    1800    IN      CNAME   login2.opensuse.org.
login2.opensuse.org.    1800    IN      A       195.135.221.161

;; Query time: 75 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sun Mar 13 11:28:28 CET 2022
;; MSG SIZE  rcvd: 85


homePC:/home/kristijan # dig forums.opensuse.org @192.168.1.1

; <<>> DiG 9.16.25 <<>> forums.opensuse.org @192.168.1.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10966
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;forums.opensuse.org.           IN      A

;; ANSWER SECTION:
forums.opensuse.org.    1355    IN      CNAME   login2.opensuse.org.
login2.opensuse.org.    1355    IN      A       195.135.221.161

;; Query time: 3 msec
;; SERVER: 192.168.1.1#53(192.168.1.1)
;; WHEN: Sun Mar 13 11:28:33 CET 2022
;; MSG SIZE  rcvd: 74

homePC:/home/kristijan # ping google.com
ping: google.com: Name or service not known
homePC:/home/kristijan # nslookup google.com
^C

After i start systemd-resolved

homePC:/home/kristijan # systemctl start systemd-resolved


homePC:/home/kristijan # resolvectl
Global
       Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: uplink

Link 2 (eno1)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
Current DNS Server: 192.168.1.1
       DNS Servers: 192.168.1.1

Link 3 (anbox0)
Current Scopes: none
     Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported

homePC:/home/kristijan # dig forums.opensuse.org @192.168.1.1

; <<>> DiG 9.16.25 <<>> forums.opensuse.org @192.168.1.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22732
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;forums.opensuse.org.           IN      A

;; ANSWER SECTION:
forums.opensuse.org.    1179    IN      CNAME   login2.opensuse.org.
login2.opensuse.org.    1179    IN      A       195.135.221.161

;; Query time: 3 msec
;; SERVER: 192.168.1.1#53(192.168.1.1)
;; WHEN: Sun Mar 13 11:31:30 CET 2022
;; MSG SIZE  rcvd: 74


homePC:/home/kristijan # dig @8.8.8.8 forums.opensuse.org

; <<>> DiG 9.16.25 <<>> @8.8.8.8 forums.opensuse.org
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54279
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;forums.opensuse.org.           IN      A

;; ANSWER SECTION:
forums.opensuse.org.    554     IN      CNAME   login2.opensuse.org.
login2.opensuse.org.    554     IN      A       195.135.221.161

;; Query time: 19 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sun Mar 13 11:31:35 CET 2022
;; MSG SIZE  rcvd: 85


homePC:/home/kristijan # ping google.com
PING google.com (172.217.20.14) 56(84) bytes of data.
64 bytes from bud02s28-in-f14.1e100.net (172.217.20.14): icmp_seq=1 ttl=118 time=7.00 ms
64 bytes from bud02s28-in-f14.1e100.net (172.217.20.14): icmp_seq=2 ttl=118 time=6.86 ms
^C
--- google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 6.861/6.930/6.999/0.069 ms

I have just noticeed that in Yast->Networking->Network Setup Method was Network Service Disabled and ther was no entrys in DNS…
I have changed Network Setup Method to Network Manager

I have used https://en.opensuse.org/SDB:Configure_DNS and add rc-manager=file

Without systemd-resolved enabled DNS is not working.

This cought my eye

homePC:/home/kristijan # nano /etc/systemd/resolved.conf
homePC:/home/kristijan # systemctl status  systemd-resolved
● systemd-resolved.service - Network Name Resolution
     Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: disabled)
     Active: active (running) since Sun 2022-03-13 12:31:01 CET; 4h 49min ago
       Docs: man:systemd-resolved.service(8)
             man:org.freedesktop.resolve1(5)
             https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers
             https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients
   Main PID: 1357 (systemd-resolve)
     Status: "Processing requests..."
      Tasks: 1 (limit: 4915)
        CPU: 162ms
     CGroup: /system.slice/systemd-resolved.service
             └─1357 /usr/lib/systemd/systemd-resolved

Mar 13 14:04:39 homePC systemd-resolved[1357]: Using degraded feature set UDP instead of UDP+EDNS0 for DNS server 192.168.1.1.
Mar 13 15:34:39 homePC systemd-resolved[1357]: Grace period over, resuming full feature set (UDP+EDNS0) for DNS server 192.168.1.1.
Mar 13 15:40:02 homePC systemd-resolved[1357]: Using degraded feature set UDP instead of UDP+EDNS0 for DNS server 192.168.1.1.
Mar 13 17:13:45 homePC systemd-resolved[1357]: eno1: Bus client reset search domain list.
Mar 13 17:13:45 homePC systemd-resolved[1357]: eno1: Bus client set default route setting: no
Mar 13 17:13:45 homePC systemd-resolved[1357]: eno1: Bus client reset DNS server list.
Mar 13 17:13:55 homePC systemd-resolved[1357]: eno1: Bus client set search domain list to: 192.168.1.1
Mar 13 17:13:55 homePC systemd-resolved[1357]: eno1: Bus client set default route setting: yes
Mar 13 17:13:55 homePC systemd-resolved[1357]: eno1: Bus client set DNS server list to: 192.168.1.1
**Mar 13 17:13:59 homePC systemd-resolved[1357]: Using degraded feature set UDP instead of UDP+EDNS0 for DNS server 192.168.1.1.**

homePC:/home/kristijan # systemctl restart systemd-resolved
homePC:/home/kristijan # systemctl status  systemd-resolved
● systemd-resolved.service - Network Name Resolution
     Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: disabled)
     Active: active (running) since Sun 2022-03-13 17:20:33 CET; 3s ago
       Docs: man:systemd-resolved.service(8)
             man:org.freedesktop.resolve1(5)
             https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers
             https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients
   Main PID: 8142 (systemd-resolve)
     Status: "Processing requests..."
      Tasks: 1 (limit: 4915)
        CPU: 79ms
     CGroup: /system.slice/systemd-resolved.service
             └─8142 /usr/lib/systemd/systemd-resolved

Mar 13 17:20:33 homePC systemd[1]: Starting Network Name Resolution...
Mar 13 17:20:33 homePC systemd-resolved[8142]: Positive Trust Anchors:
Mar 13 17:20:33 homePC systemd-resolved[8142]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d
Mar 13 17:20:33 homePC systemd-resolved[8142]: Negative trust anchors: home.arpa 10.in-addr.arpa 16.172.in-addr.arpa 17.172.in-addr.arpa 18.172.in-addr.arpa 19.172.in>
Mar 13 17:20:33 homePC systemd-resolved[8142]: Using system hostname 'homePC'.
Mar 13 17:20:33 homePC systemd[1]: Started Network Name Resolution.

I also found that (Using degraded feature set UDP instead of UDP+EDNS0 for DNS server 192.168.1.1.) is wide spread on debian, fedora…
And they all have exactly the same problem with randomly disconnecting DNS.
So i un commented in /etc/systemd/resolved.conf line DNSSEC=no as sugested as fix.
https://superuser.com/questions/1676584/using-degraded-feature-set-tcp-instead-of-udp-for-dns-server
https://github.com/systemd/systemd/issues/13432
https://www.linuxquestions.org/questions/linux-networking-3/systemd-resolved-using-degraded-feature-set-tcp-instead-of-udp-for-dns-server-4175693509/

As i am writhing this here it is again “Using degraded feature set UDP instead of UDP+EDNS0 for DNS…”

But DNS is working…

I have to start systemd-resolved to get DNS working, after that i can stop systemd-resolved and DNS is still working… for some time

14

You may enable systemd-resolved:

**erlangen:~ #** systemctl list-unit-files systemd-resolved.service 
UNIT FILE                STATE   VENDOR PRESET
systemd-resolved.service **enabled ****disabled     **

1 unit files listed. 
**erlangen:~ #**

Status messages of working Network Name Resolution

**erlangen:~ #** systemctl status systemd-resolved.service --no-pager --full  
**●** systemd-resolved.service - Network Name Resolution 
     Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: disabled) 
     Active: **active (running)** since Mon 2022-03-14 05:48:58 CET; 1h 9min ago 
       Docs: man:systemd-resolved.service(8) 
             man:org.freedesktop.resolve1(5) 
             https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers 
             https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients 
   Main PID: 720 (systemd-resolve) 
     Status: "Processing requests..." 
      Tasks: 1 (limit: 4915) 
        CPU: 118ms 
     CGroup: /system.slice/systemd-resolved.service 
             └─720 /usr/lib/systemd/systemd-resolved 

Mar 14 05:48:58 erlangen systemd[1]: Starting Network Name Resolution... 
Mar 14 05:48:58 erlangen systemd-resolved[720]: Positive Trust Anchors: 
Mar 14 05:48:58 erlangen systemd-resolved[720]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d 
Mar 14 05:48:58 erlangen systemd-resolved[720]: Negative trust anchors: home.arpa 10.in-addr.arpa 16.172.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 168.192.in-addr.arpa d.f.ip6.arpa corp home internal intranet lan local private test 
Mar 14 05:48:58 erlangen systemd-resolved[720]: Using system hostname 'erlangen'. 
Mar 14 05:48:58 erlangen systemd[1]: Started Network Name Resolution. 
**erlangen:~ #**