problem getting address record for google public dns server
Stacey Jonathan Marshall
stacey.marshall at oracle.com
Wed Nov 17 10:01:13 UTC 2010
This crops up time and time again - perhaps +trace should have been +mimic.
The '+trace' option causes dig to act as a recursive server would,
asking each server in turn for a none recursive answer. Thus when you
say +trace its your instance of dig that's doing the work.
The details in the response hold your answer:
$ dig @66.231.91.222 google-public-dns-a.google.com
; <<>> DiG 9.3.6-P1 <<>> @66.231.91.222 google-public-dns-a.google.com
; (1 server found)
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 503
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 0
;; QUESTION SECTION:
;google-public-dns-a.google.com. IN A
;; AUTHORITY SECTION:
. 3600000 IN NS A.ROOT-SERVERS.NET.
. 3600000 IN NS B.ROOT-SERVERS.NET.
. 3600000 IN NS C.ROOT-SERVERS.NET.
. 3600000 IN NS D.ROOT-SERVERS.NET.
. 3600000 IN NS E.ROOT-SERVERS.NET.
. 3600000 IN NS F.ROOT-SERVERS.NET.
. 3600000 IN NS G.ROOT-SERVERS.NET.
. 3600000 IN NS H.ROOT-SERVERS.NET.
. 3600000 IN NS I.ROOT-SERVERS.NET.
. 3600000 IN NS J.ROOT-SERVERS.NET.
. 3600000 IN NS K.ROOT-SERVERS.NET.
. 3600000 IN NS L.ROOT-SERVERS.NET.
. 3600000 IN NS M.ROOT-SERVERS.NET.
;; Query time: 111 msec
;; SERVER: 66.231.91.222#53(66.231.91.222)
;; WHEN: Wed Nov 17 09:50:35 2010
;; MSG SIZE rcvd: 259
Looking at the flags in the response note the lack of 'ra'; Recursion
Available!
Thus the server is saying I don't know (or I wont tell you what's in my
cache) and I'm not going to find an answer for you, go start looking at
the root servers. Hence the +trace works.
Regards
Stacey
On 16/11/2010 21:00, M. Meadows wrote:
> Can someone explain the following dig results? The first dig @8.8.8.8
> provides the expected result
>
>
> : dig +noall +answer google-public-dns-a.google.com @8.8.8.8
> google-public-dns-a.google.com. 85040 IN A 8.8.8.8
>
> We get the same result from KLOTH.NET
> (http://www.kloth.net/services/nslookup.php)
>
>
> But when we specify the public facing exacttarget.com server
>
> : dig +noall +answer google-public-dns-a.google.com @66.231.91.222
>
> No answer
>
> And when we use +trace ... it seems to find it's way to the correct
> answer.
>
> : dig google-public-dns-a.google.com @66.231.91.222 +trace
> ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_4.2 <<>>
> google-public-dns-a.google.com @66.231.91.222 +trace
> ;; global options: printcmd
> . 3600000 IN NS A.ROOT-SERVERS.NET.
> . 3600000 IN NS B.ROOT-SERVERS.NET.
> . 3600000 IN NS C.ROOT-SERVERS.NET.
> . 3600000 IN NS D.ROOT-SERVERS.NET.
> . 3600000 IN NS E.ROOT-SERVERS.NET.
> . 3600000 IN NS F.ROOT-SERVERS.NET.
> . 3600000 IN NS G.ROOT-SERVERS.NET.
> . 3600000 IN NS H.ROOT-SERVERS.NET.
> . 3600000 IN NS I.ROOT-SERVERS.NET.
> . 3600000 IN NS J.ROOT-SERVERS.NET.
> . 3600000 IN NS K.ROOT-SERVERS.NET.
> . 3600000 IN NS L.ROOT-SERVERS.NET.
> . 3600000 IN NS M.ROOT-SERVERS.NET.
> ;; Received 228 bytes from 66.231.91.222#53(66.231.91.222) in 1 ms
> com. 172800 IN NS g.gtld-servers.net.
> com. 172800 IN NS f.gtld-servers.net.
> com. 172800 IN NS l.gtld-servers.net.
> com. 172800 IN NS h.gtld-servers.net.
> com. 172800 IN NS j.gtld-servers.net.
> com. 172800 IN NS c.gtld-servers.net.
> com. 172800 IN NS i.gtld-servers.net.
> com. 172800 IN NS d.gtld-servers.net.
> com. 172800 IN NS k.gtld-servers.net.
> com. 172800 IN NS m.gtld-servers.net.
> com. 172800 IN NS a.gtld-servers.net.
> com. 172800 IN NS e.gtld-servers.net.
> com. 172800 IN NS b.gtld-servers.net.
> ;; Received 504 bytes from 198.41.0.4#53(A.ROOT-SERVERS.NET) in 35 ms
> google.com. 172800 IN NS ns2.google.com.
> google.com. 172800 IN NS ns1.google.com.
> google.com. 172800 IN NS ns3.google.com.
> google.com. 172800 IN NS ns4.google.com.
> ;; Received 184 bytes from 192.42.93.30#53(g.gtld-servers.net) in 75 ms
> google-public-dns-a.google.com. 86400 IN A 8.8.8.8
> ;; Received 64 bytes from 216.239.34.10#53(ns2.google.com) in 39 ms
>
> What's going on?
>
> Thanks!
> Marty
>
>
>
>
>
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