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my /etc/resolv.conf use and all 3 dig below answers without a A reocrd

dig some_unregistred_adress.se
dig @ some_unregistred_adress.se
dig @ some_unregistred_adress.se

but if i ping some_unregistred_adress.se i end up pinging my server, thats not even at the same ISP as this computer, only connection i know is that this computers hostname is a subdomain of my server.

Where is ping and other softwhere geting the IP adresses from unregistered domains?

some relevant output:

puggan@rito ~ $ uname -a
Linux rito.work.puggan.se 2.6.38-gentoo-r6 #2 SMP Thu Jul 14 14:36:14 CEST 2011 i686 AMD Athlon(tm) II X2 245 Processor AuthenticAMD GNU/Linux

puggan@rito ~ $ dig @ some_unregistred_adress.se

; <<>> DiG 9.7.3 <<>> @ some_unregistred_adress.se
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 8080
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;some_unregistred_adress.se.    IN      A

;; Query time: 0 msec
;; WHEN: Fri Dec  2 15:51:31 2011
;; MSG SIZE  rcvd: 44

puggan@rito ~ $ ping -c 1 some_unregistred_adress.se
PING puggan.se ( 56(84) bytes of data.
64 bytes from c83-248-176-173.bredband.comhem.se ( icmp_req=1 ttl=52 time=34.4 ms

--- puggan.se ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 34.406/34.406/34.406/0.000 ms

puggan@rito ~ $ egrep "^(#|$)" -v /etc/resolv.conf
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migrated from stackoverflow.com Dec 2 '11 at 16:34

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Anything in /etc/hosts? –  Matti Virkkunen Dec 2 '11 at 15:16
nothing relevant: egrep "^(#|$)" -v /etc/hosts localhost guide.opendns.com ::1 localhost maple-info.net www.maple-info.net mrzoom-egotripp –  Puggan Se Dec 2 '11 at 15:17
Marc B: yes, but dig should be catched to then, as opendns do, if i ran "dig @ some_unregistred_adress.se" i get a false A record –  Puggan Se Dec 2 '11 at 15:18

3 Answers 3

up vote 2 down vote accepted
  1. You are not using fully-qualified domain names;
  2. your domain search path for converting names to FQDNs includes puggan.se.; and
  3. there is a wildcard at *.puggan.se that matches some_unregistred_adress.se.puggan.se. and that has a cname resource record set pointing to puggan.se.

Use fully-qualified domain names if you don't want to use the search path behaviour that you have configured in your DNS client library.

Further reading

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Some ISPs intercept DNS requests and redirect them to their own, and serve up bad answers (e.g. their own spamvertising sites) in the hopes of making a few pennies off nonexistent/mis-typed domains.

As well, whoever's running the .se TLD can also have a wildcard *.se DNS entry to catch all non-existent .se domain lookups as well. For .se, this seems to be "one.com":

$ nslookup -type=soa blahblah.se
Server:  access.usask.ca

Non-authoritative answer:
        primary name server = ns01.one.com
        responsible mail addr = hostmaster.one.com
        serial  = 2004000000
        refresh = 10800 (3 hours)
        retry   = 1800 (30 mins)
        expire  = 1209600 (14 days)
        default TTL = 900 (15 mins)

blahblah.se     nameserver = ns01.one.com
blahblah.se     nameserver = ns02.one.com
ns01.one.com    internet address =
ns02.one.com    internet address =</strike>

ok... should've picked a way more random/non-existent domain for this particular test. nslookup asdfasdfasdfasdfasdfadsf.se does return no-such-host.

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nslookup -type=soa some_unregistred_adress.se Server: Address: ** server can't find some_unregistred_adress.se: NXDOMAIN –  Puggan Se Dec 2 '11 at 15:21
blahblah.se is a reigistred doamin, owned by HENRIK FORSELL –  Puggan Se Dec 2 '11 at 15:22
for asdfasdfasdfasdfasdfadsf.se dig and nslookup give no a record, and ping gives me the same ip as my server –  Puggan Se Dec 2 '11 at 15:31
ping should be using the system resolver settings, so ping/telnet/traceroute/ssh/etc... should all get the same IP when they look it up. –  Marc B Dec 2 '11 at 15:46
they all have the same problem, but programs like dig and nslookup don't, and they use /etc/resolv.conf, so what backup plan are the system resolver using, i guess its using my hostname somehow, and i want to turn it off –  Puggan Se Dec 3 '11 at 17:26

Got same problem again, forgot to write my soulution last time.

to turn off search domain i added search . in /etc/dhcpcd.conf (gentoo)

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