Mailinglist Archive: opensuse (527 mails)

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Re: [opensuse] A puzzle for the weekend
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 http://office20.local.net:4444/--slope--/1.2.3.4/0
--2016-08-12 20:38:24--
http://office20.local.net:4444/--slope--/1.2.3.4/0 Resolving
office20.local.net (office20.local.net)... failed: Name or service
not known. wget: unable to resolve host address ‘office20.local.net’

So clearly "office20.local.net" does not resolve. Except:
host office20.local.net

office20.local.net has address 192.168.3.20

ping office20.local.net

PING office20.local.net (192.168.3.20) 56(84) bytes of data.
64 bytes from office20.local.net (192.168.3.20): icmp_seq=1 ttl=64
time=0.029 ms 64 bytes from office20.local.net (192.168.3.20):
icmp_seq=2 ttl=64 time=0.040 ms

dig office20.local.net a

; <<>> DiG 9.9.4-rpz2.13269.14-P2 <<>> office20.local.net 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:
3

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;office20.local.net. IN A

;; ANSWER SECTION:
office20.local.net. 86400 IN A 192.168.3.20


So clearly "office20.local.net" _does_ resolve. Except in wget.


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

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


office20.local.net

Do you really own 'local.net'? Some programs may do the lookup manually
without glibc, ignoring /etc/resolv.conf. I know that postfix does that
by default. 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.)

Could be that you are using another unwanted nameserver which you have
not configured to serve your own local.net. (autoconfig/dhcp), see
comment 6 here:
https://bugzilla.suse.com/show_bug.cgi?id=984088#c6

Some other possibilites:
- nscd issues?
- Maybe wget handles ipv4/v6 stupidly? Try wget -4.
- What queries are sent to the nameserver (and to which nameserver!)?
tcpdump -n -i eth0 port 53

cu,
Rudi
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