On Wed, Aug 23, 2017 at 4:37 PM, i mawsog via NANOG <nanog@nanog.org> wrote:
> > This is great. Thanks for sharing . > > Sent from Yahoo Mail on Android > > On Wed, Aug 23, 2017 at 1:11 PM, Erik Sundberg<esundb...@nitelusa.com> > wrote: I sent this out on the outage list, with a lots of good feedback > sent to me. So I figured it would be useful to share the information on > nanog as well. > > > A couple months ago had to troubleshoot a google DNS issue with Google’s > NOC. Below is some helpful information on how to determine which DNS > Cluster you are going to. > > Let’s remember that Google runs DNS Anycast for DNS queries to 8.8.8.8 and > 8.8.4.4. Anycast routes your DNS queries to the closes DNS cluster based on > the best route / lowest metric to 8.8.8.8/8.8.4.4. Google has deployed > multiple DNS clusters across the world and each DNS Cluster has multiple > servers. > > So a DNS query in Chicago will go to a different DNS clusters than queries > from a device in Atlanta or New York. > > > How to get a list of google DNS Cluster’s. > dig -t TXT +short locations.publicdns.goog. @8.8.8.8 > > How to print this list in a table format. Script from: > https://developers.google.com/speed/public-dns/faq > --------------- > #!/bin/bash > IFS="\"$IFS" > for LOC in $(dig -t TXT +short locations.publicdns.goog. @8.8.8.8) > do > case $LOC in > '') : ;; > *.*|*:*) printf '%s ' ${LOC} ;; > *) printf '%s\n' ${LOC} ;; > esac > done > --------------- > > Which will give you a list like below. This is all of the IP network’s > that google uses for their DNS Clusters and their associated locations. > > 74.125.18.0/26 iad > 74.125.18.64/26 iad > 74.125.18.128/26 syd > 74.125.18.192/26 lhr > 74.125.19.0/24 mrn > 74.125.41.0/24 tpe > 74.125.42.0/24 atl > 74.125.44.0/24 mrn > 74.125.45.0/24 tul > 74.125.46.0/24 lpp > 74.125.47.0/24 bru > 74.125.72.0/24 cbf > 74.125.73.0/24 bru > 74.125.74.0/24 lpp > 74.125.75.0/24 chs > 74.125.76.0/24 cbf > 74.125.77.0/24 chs > 74.125.79.0/24 lpp > 74.125.80.0/24 dls > 74.125.81.0/24 dub > 74.125.92.0/24 mrn > 74.125.93.0/24 cbf > 74.125.112.0/24 lpp > 74.125.113.0/24 cbf > 74.125.115.0/24 tul > 74.125.176.0/24 mrn > 74.125.177.0/24 atl > 74.125.179.0/24 cbf > 74.125.181.0/24 bru > 74.125.182.0/24 cbf > 74.125.183.0/24 cbf > 74.125.184.0/24 chs > 74.125.186.0/24 dls > 74.125.187.0/24 dls > 74.125.190.0/24 sin > 74.125.191.0/24 tul > 172.217.32.0/26 lhr > 172.217.32.64/26 lhr > 172.217.32.128/26 sin > 172.217.33.0/26 syd > 172.217.33.64/26 syd > 172.217.33.128/26 fra > 172.217.33.192/26 fra > 172.217.34.0/26 fra > 172.217.34.64/26 bom > 172.217.34.192/26 bom > 172.217.35.0/24 gru > 172.217.36.0/24 atl > 172.217.37.0/24 gru > 173.194.90.0/24 cbf > 173.194.91.0/24 scl > 173.194.93.0/24 tpe > 173.194.94.0/24 cbf > 173.194.95.0/24 tul > 173.194.97.0/24 chs > 173.194.98.0/24 lpp > 173.194.99.0/24 tul > 173.194.100.0/24 mrn > 173.194.101.0/24 tul > 173.194.102.0/24 atl > 173.194.103.0/24 cbf > 173.194.168.0/26 nrt > 173.194.168.64/26 nrt > 173.194.168.128/26 nrt > 173.194.168.192/26 iad > 173.194.169.0/24 grq > 173.194.170.0/24 grq > 173.194.171.0/24 tpe > 2404:6800:4000::/48 bom > 2404:6800:4003::/48 sin > 2404:6800:4006::/48 syd > 2404:6800:4008::/48 tpe > 2404:6800:400b::/48 nrt > 2607:f8b0:4001::/48 cbf > 2607:f8b0:4002::/48 atl > 2607:f8b0:4003::/48 tul > 2607:f8b0:4004::/48 iad > 2607:f8b0:400c::/48 chs > 2607:f8b0:400d::/48 mrn > 2607:f8b0:400e::/48 dls > 2800:3f0:4001::/48 gru > 2800:3f0:4003::/48 scl > 2a00:1450:4001::/48 fra > 2a00:1450:4009::/48 lhr > 2a00:1450:400b::/48 dub > 2a00:1450:400c::/48 bru > 2a00:1450:4010::/48 lpp > 2a00:1450:4013::/48 grq > > isn't this list also here: https://developers.google.com/speed/public-dns/faq#locations I mean, you could read the docs first to get the same answer, I think... right? I'm also pretty sure there are RIPE Atlas measurements of 8.8.8.8/8.8.4.4 that could tell you from which source-asn a backend sees traffic from.. right? (or with a tiny bit of thought one could be proposed/executed) > There are > IPv4 Networks: 68 > IPv6 Networks: 20 > DNS Cluster’s Identified by POP Code’s: 20 > > DNS Clusters identified by POP Code to City, State, or Country. Not all of > these are Google’s Core Datacenters, some of them are Edge Points of > Presences (POPs). https://peering.google.com/#/infrastructure and > https://www.google.com/about/datacenters/inside/locations/ > > Most of these are airport codes, it did my best to get the location > correct. > iad Washington, DC > syd Sydney, Australia > lhr London, UK > mrn Lenoir, NC > tpe Taiwan > atl Altanta, GA > tul Tulsa, OK > lpp Findland > bru Brussels, Belgium > cbf Council Bluffs, IA > chs Charleston, SC > dls The Dalles, Oregon > dub Dublin, Ireland > sin Singapore > fra Frankfort, Germany > bom Mumbai, India > gru Sao Paulo, Brazil > scl Santiago, Chile > nrt Tokyo, Japan > grq Groningen, Netherlans > > > > Which Google DNS Server Cluster am I using. I am testing this from > Chicago, IL > > # dig o-o.myaddr.l.google.com -t txt +short @8.8.8.8 > "173.194.94.135" <<<<<<DNS Server IP, reference the > list above to get the cluster, Council Bluffs, IA > "edns0-client-subnet 207.xxx.xxx.0/24" > <<<< Your Source IP Block > > > Side note, the google dns servers will not respond to DNS queries to the > Cluster’s Member’s IP, they will only respond to dns queries to 8.8.8.8 and > 8.8.4.4. So the following will not work. > dig google.com @173.194.94.135 > > > > Now to see the DNS Cluster load balancing in action. I am doing a dig > query from our Telx\Digital Realty POP in Atlanta, GA. We do peer with > google at this location. > > I dig a dig query about 10 times and received the following unique dns > cluster member ip’s as responses. > > dig o-o.myaddr.l.google.com -t txt +short @8.8.8.8 > "74.125.42.138" > "173.194.102.132" > "74.125.177.5" > "74.125.177.74" > "74.125.177.71" > "74.125.177.4" > > Which all are Google DNS Networks in Atlanta. > 74.125.42.0/24 > > atl > > 74.125.177.0/24 > > atl > > 172.217.36.0/24 > > atl > > 173.194.102.0/24 > > atl > > 2607:f8b0:4002::/48 > > atl > > > > Just thought it would be helpful when troubleshooting google DNS issues. > > > ________________________________ > > CONFIDENTIALITY NOTICE: This e-mail transmission, and any documents, files > or previous e-mail messages attached to it may contain confidential > information that is legally privileged. If you are not the intended > recipient, or a person responsible for delivering it to the intended > recipient, you are hereby notified that any disclosure, copying, > distribution or use of any of the information contained in or attached to > this transmission is STRICTLY PROHIBITED. If you have received this > transmission in error please notify the sender immediately by replying to > this e-mail. You must destroy the original transmission and its attachments > without reading or saving in any manner. Thank you. > >
