systemd-resolved not starting on boot

When I boot my Ubuntu server, DNS resolving does not work. You can most easily see this by looking at resolv.conf:

~ # cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.

I then enable the resolved service:

~ # systemctl enable systemd-resolved.service

And things work as expected:

~ # cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.
nameserver 127.0.0.53

Config

• Ubuntu 19.04
• 5.0.0-23-generic

Related packages installed:

~ # cat /etc/resodpkg -l |grep systemd
ii libnss-resolve:amd64 240-6ubuntu5.2 amd64 nss module to resolve names via systemd-resolved
ii libnss-systemd:amd64 240-6ubuntu5.2 amd64 nss module providing dynamic user and group name resolution
ii libpam-systemd:amd64 240-6ubuntu5.2 amd64 system and service manager - PAM module
ii libsystemd0:amd64 240-6ubuntu5.2 amd64 systemd utility library
ii networkd-dispatcher 2.0-2 all Dispatcher service for systemd-networkd connection status changes
ii python3-systemd 234-2build2 amd64 Python 3 bindings for systemd
ii systemd 240-6ubuntu5.2 amd64 system and service manager
ii systemd-sysv 240-6ubuntu5.2 amd64 system and service manager - SysV links
~ # dpkg -l |grepdpkg -l |grep resolv
ii libc-ares2:amd64 1.14.0-1 amd64 asynchronous name resolver
ii libgeoip1:amd64 1.6.12-1 amd64 non-DNS IP-to-country resolver library
ii libnss-resolve:amd64 240-6ubuntu5.2 amd64 nss module to resolve names via systemd-resolved
ii resolvconf 1.79ubuntu13 all name server information handler

Name resolution worked on boot prior to updating to 19.04.

No apparent errors in syslog. Related excerpt:

Aug 3 11:41:16 green systemd[1]: Starting Network Name Resolution...
Aug 3 11:41:16 green systemd-resolved[807]: Positive Trust Anchors:
Aug 3 11:41:16 green systemd-resolved[807]: . IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5
Aug 3 11:41:16 green systemd-resolved[807]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d
Aug 3 11:41:16 green systemd-resolved[807]: Negative trust anchors: 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.arp
Aug 3 11:41:16 green systemd[1]: Started Network Name Resolution.

Status before reboot (with nameserver listed in /etc/resolv.conf):

~ # systemctl status systemd-resolved.service
● systemd-resolved.service - Network Name Resolution Loaded: loaded (/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: enabled) Active: active (running) since Sat 2019-08-03 11:39:32 EDT; 2 days ago Docs: man:systemd-resolved.service(8) Main PID: 807 (systemd-resolve) Status: "Processing requests..." Tasks: 1 (limit: 4915) Memory: 7.9M CGroup: / └─807 /lib/systemd/systemd-resolved
Aug 06 10:00:38 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:04:06 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:04:06 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:04:06 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:04:06 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:15:53 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:17:05 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:17:05 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:17:05 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:17:05 green systemd-resolved[807]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature

Status before reboot (with nothing listed in /etc/resolv.conf):

~ # systemctl status systemd-resolved.service
● systemd-resolved.service - Network Name Resolution Loaded: loaded (/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: enabled) Active: active (running) since Tue 2019-08-06 10:23:53 EDT; 1min 9s ago Docs: man:systemd-resolved.service(8) Main PID: 798 (systemd-resolve) Status: "Processing requests..." Tasks: 1 (limit: 4915) Memory: 7.8M CGroup: / └─798 /lib/systemd/systemd-resolved
Aug 06 10:23:51 green systemd[1]: Starting Network Name Resolution...
Aug 06 10:23:52 green systemd-resolved[798]: Positive Trust Anchors:
Aug 06 10:23:52 green systemd-resolved[798]: . IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5
Aug 06 10:23:52 green systemd-resolved[798]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d
Aug 06 10:23:52 green systemd-resolved[798]: Negative trust anchors: 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.
Aug 06 10:23:52 green systemd-resolved[798]: Using system hostname 'green'.
Aug 06 10:23:53 green systemd[1]: Started Network Name Resolution.
~ # systemd-resolve --status
Global LLMNR setting: no
MulticastDNS setting: no DNSOverTLS setting: no DNSSEC setting: no DNSSEC supported: no Current DNS Server: 8.8.8.8 DNS Servers: 8.8.8.8 8.8.4.4 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 3 (eno2) Current Scopes: none
DefaultRoute setting: no LLMNR setting: yes
MulticastDNS setting: no DNSOverTLS setting: no DNSSEC setting: no DNSSEC supported: no
Link 2 (eno1) Current Scopes: none
DefaultRoute setting: no LLMNR setting: yes
MulticastDNS setting: no DNSOverTLS setting: no DNSSEC setting: no DNSSEC supported: no

After systemctl enable systemd-resolved.service(with nameserver listed in /etc/resolv.conf):

~ # systemctl status systemd-resolved.service
● systemd-resolved.service - Network Name Resolution Loaded: loaded (/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: enabled) Active: active (running) since Tue 2019-08-06 10:23:53 EDT; 3min 47s ago Docs: man:systemd-resolved.service(8) Main PID: 798 (systemd-resolve) Status: "Processing requests..." Tasks: 1 (limit: 4915) Memory: 7.9M CGroup: / └─798 /lib/systemd/systemd-resolved
Aug 06 10:23:52 green systemd-resolved[798]: Positive Trust Anchors:
Aug 06 10:23:52 green systemd-resolved[798]: . IN DS 19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5
Aug 06 10:23:52 green systemd-resolved[798]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d
Aug 06 10:23:52 green systemd-resolved[798]: Negative trust anchors: 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.
Aug 06 10:23:52 green systemd-resolved[798]: Using system hostname 'green'.
Aug 06 10:23:53 green systemd[1]: Started Network Name Resolution.
Aug 06 10:27:32 green systemd-resolved[798]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:27:35 green systemd-resolved[798]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:27:35 green systemd-resolved[798]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature
Aug 06 10:27:35 green systemd-resolved[798]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature

systemd-resolve --status shows the same as before.

1 Answer

You installed something like resolvconf which cuts sytemd-resolved off entirely by commenting out the 53 listening address in stub-resolv.conf which the /etc/resolv.conf should link to.For a fresh Ubuntu 18.04 install, the only additional name resolution package I needed was libnss-resolve. I never use resolvconf, so don't know why you need it.