Mailinglist Archive: opensuse (527 mails)

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Re: [opensuse] A puzzle for the weekend
  • From: Per Jessen <per@xxxxxxxxxxxx>
  • Date: Sat, 13 Aug 2016 10:22:52 +0200
  • Message-id: <nomlcs$tl5$>
Ruediger Meier wrote:

On Friday 12 August 2016, Per Jessen wrote:
I have a cron job running every 20 minutes monitoring a temperature
sensor for minor changes in trend up/down. This has been running for
a few months.

Today at 1521 I got a warning that the trend dad changed to
slightly upward. The next one failed on a DNS issue.

The puzzle:

wget -nd
--2016-08-12 20:38:24-- Resolving ( failed: Name or service
not known. wget: unable to resolve host address ‘’

So clearly "" does not resolve. Except:
host has address


PING ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=64
time=0.029 ms 64 bytes from (
icmp_seq=2 ttl=64 time=0.040 ms

dig a

; <<>> DiG 9.9.4-rpz2.13269.14-P2 <<>> a
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 30802
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL:

; EDNS: version: 0, flags:; udp: 4096
; IN A


So clearly "" _does_ resolve. Except in wget.

No changes were applied to this system for at least a month, likely

Why can't wget resolve the address when others have no problem?

Do you really own ''?

Hehe, nono. That one is only used locally on

Some programs may do the lookup manually without glibc,
ignoring /etc/resolv.conf. I know that postfix does that by default.

Are you sure? At least it couldn't do it without /etc/resolv.conf, and
I'm pretty certain my installations also use /etc/hosts (which is handy
for overrides).

You should better not use domains which you don't own! Or at least a
top level domain which does not exist (hard to find one nowadays.)

I agree completely, but '' has been used internally for maybe
15 years, and changing it to something truly local would mean a lot of
checking and double-checking.

Could be that you are using another unwanted nameserver which you have
not configured to serve your own (autoconfig/dhcp),

Check, /etc/resolv.conf is fine.

Some other possibilites:
- nscd issues?

I did think of that one, and did "nscd -i hosts" - however, ping will
also use nscd, and that works.

- Maybe wget handles ipv4/v6 stupidly? Try wget -4.

Ah, forgot about that one. Yes! that was it.

What remains of the puzzle - why did this suddenly start yesterday at
15:21 after running fine since April? I swear that machine was not
touched. I don't really want to add that '-4' as it shouldn't be
necessary. Anyway, thanks for mentioning that. I'll have to look a
little closer at wget.

Per Jessen, Zürich (17.1°C) - dedicated server rental in Switzerland.

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