(this is -almost- a copy / paste of an email sent by Erik Sundberg to nanog mailing list on August 23).
This post is being posted with his explicit permission.
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 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" <<<<<dig o-o.myaddr.l.google.com -t
"74.125.42.138" "173.194.102.132" "74.125.177.5" "74.125.177.74" "74.125.177.71"txt +short @8.8.8.8
"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.
Just thought it would be helpful when troubleshooting google DNS issues.
(one more time: this is -almost- a copy / paste of an email sent by Erik Sundberg to nanog mailing list on August 23). This post is being posted with his explicit permission.
