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# env
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.5 LTS
Release:        18.04
Codename:       bionic

$ systemd-resolve --vers
systemd 237
+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybrid

I noticed that some DNS queries failed, syslog says like at that time:

Apr 22 03:39:40 <hostname> systemd-resolved[1113]: Grace period over, resuming full feature set (UDP+EDNS0) for DNS server 10.27.32.5.
Apr 22 03:39:52 <hostname> systemd-resolved[1113]: Using degraded feature set (UDP) for DNS server 10.27.32.5.

I can check the above logs not only at that time but also in sometimes about a couple of times in a day or week. But not every moment of them raised the failures of DNS queries.

In this situation, where can I dig it from?

Is it possible that edns0 option occur the failures of DNS queries?

+ My resolve.conf is very simple. Only for private DNS:

$ cat /etc/resolv.conf
nameserver <private.dns.ip>
options edns0
search localnet
홍한석
  • 101
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  • You should make sure the remote nameserver handles EDNS correctly, which should be the case for any standard recent one configured normally. You probably can not test it remotely (if you can, just use https://ednscomp.isc.org/ednscomp) so grab the `genreport` tool from https://gitlab.isc.org/isc-projects/DNS-Compliance-Testing and run it yourself. – Patrick Mevzek May 03 '22 at 14:05

0 Answers0