Google DNS --- Figuring out which DNS Cluster you are using

Erik Sundberg ESundberg at
Thu Aug 24 04:41:21 UTC 2017

Shaun, Good catch!!!

I would be nice if this was lowered to 1 second.

#dig -t txt  @
;; ANSWER SECTION: 51     IN      TXT     "" 51     IN      TXT     "edns0-client-subnet"   <<< Not my ip but someone from this IP did query this 9 seconds ago.

-----Original Message-----
From: Shaun [mailto:nanog at]
Sent: Wednesday, August 23, 2017 11:21 PM
To: Erik Sundberg
Cc: nanog at
Subject: Re: Google DNS --- Figuring out which DNS Cluster you are using

On Wed, 23 Aug 2017 20:09:49 +0000
Erik Sundberg <ESundberg at> wrote:

> Which Google DNS Server Cluster am I using. I am testing this from
> Chicago, IL
> # dig -t txt +short @
> ""                     <<<<<<DNS Server IP, reference the list above to get the cluster, Council Bluffs, IA
> "edns0-client-subnet"                                  <<<< Your Source IP Block

Worth noting, this record has TTL 60 and caching can cause unexpected responses; you may have to try a few times to get the correct data. My first attempt gave me an unrecognized "edns0-client-subnet" and a Google IP from Finland when I was querying from Atlanta.



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