Google DNS --- Figuring out which DNS Cluster you are using
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" <<<<<<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.
This is great. Thanks for sharing . Sent from Yahoo Mail on Android On Wed, Aug 23, 2017 at 1:11 PM, Erik Sundberg<ESundberg@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 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.
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<ESundberg@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.
Gee Chris, that's kind of an asinine response. Erik took the time to let us know about what he had found out, with a nice code snippet too. I don't have time in my job to just go surfing around google.com to see what is there. His mail took me about 2 minutes to read and now I know that such info exists. Thank you Erik! -- Joe Hamelin, W7COM, Tulalip, WA, +1 (360) 474-7474 On Wed, Aug 23, 2017 at 5:10 PM, Christopher Morrow <morrowc.lists@gmail.com
wrote:
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<ESundberg@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.
On Wed, Aug 23, 2017 at 8:30 PM, Joe Hamelin <joe@nethead.com> wrote:
Gee Chris, that's kind of an asinine response. Erik took the time to let us know about what he had found out, with
sure, except I think the link has even been posted to nanog in the past. My point was really: it's documented, so you don't have to do the work. -chris a nice code snippet too. I don't have time in my job to just go surfing
around google.com to see what is there. His mail took me about 2 minutes to read and now I know that such info exists.
Thank you Erik!
-- Joe Hamelin, W7COM, Tulalip, WA, +1 (360) 474-7474 <(360)%20474-7474>
On Wed, Aug 23, 2017 at 5:10 PM, Christopher Morrow < morrowc.lists@gmail.com> wrote:
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<ESundberg@nitelusa.com
wrote: I sent this out on the outage list, with a lots of good
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
feedback 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.
If Google was being sensible the servers would just return the information along with the answer. They all support EDNS. e.g. dig +nsid @8.8.8.8 This is the type of thing the NSID (RFC 5001) was designed to do. It just requires Google to configure the servers to return a id. You would then back something like this. In this case the nsid is the hostname but it can be anything you like it to be. A value that makes sense to most people or a value that only make sense to a Google. ; <<>> DiG 9.12.0-pre-alpha+hotspot+add-prefetch+marka <<>> +nsid . ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 38770 ;; flags: qr rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ; NSID: 72 6f 63 6b 2e 64 76 2e 69 73 63 2e 6f 72 67 ("rock.dv.isc.org") ; COOKIE: f58c358da14bc19476e2331f599e21c452df41a06367d78d (good) ;; QUESTION SECTION: ;. IN A ;; AUTHORITY SECTION: . 10773 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2017082301 1800 900 604800 86400 ;; Query time: 0 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN: Thu Aug 24 10:45:56 AEST 2017 ;; MSG SIZE rcvd: 150 -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@isc.org
On Thu, Aug 24, 2017 at 10:53:58AM +1000, Mark Andrews <marka@isc.org> wrote a message of 39 lines which said:
If Google was being sensible the servers would just return the information along with the answer. They all support EDNS.
I fully agree with you that NSID (RFC 5001) is great and Google should really deploy it. However:
e.g. dig +nsid @8.8.8.8
I assume that Google wants also to be debuggable by people who work on inferior operating systems, and have no dig. Hence this trick. For instance, L.root-servers.net has both NSID and a special name, identity.l.root-servers.org (see RFC 7108).
Stephane Bortzmeyer <bortzmeyer@nic.fr> writes:
On Thu, Aug 24, 2017 at 10:53:58AM +1000, Mark Andrews <marka@isc.org> wrote a message of 39 lines which said:
If Google was being sensible the servers would just return the information along with the answer. They all support EDNS.
I fully agree with you that NSID (RFC 5001) is great and Google should really deploy it.
+1 for NSID! Should be mandatory for anycast DNS, IMHO. I don't understand why Google haven't enabled it.
However:
e.g. dig +nsid @8.8.8.8
I assume that Google wants also to be debuggable by people who work on inferior operating systems, and have no dig. Hence this trick. For instance, L.root-servers.net has both NSID and a special name, identity.l.root-servers.org (see RFC 7108).
As you state, there is no problem providing both. Or an infinite number of special names if they like. But NSID provides something none of the special names can. Quoting the justification in the intro of RFC5001: Given that a DNS query is an idempotent operation with no retained state, it would appear that the only completely reliable way to obtain the identity of the name server that responded to a particular query is to have that name server include identifying information in the response itself. Sometimes it just isn't enough to know which server answered the previous or next requests. Bjørn
Excellent, thanks for sharing. El 23/8/17 a las 4:09 p.m., Erik Sundberg escribió:
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" <<<<<<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.
All.. You're welcome for the info. Let's remember what NANOG is about "mailing list is established to provide a forum for the exchange of technical information and the discussion of specific implementation issues that require cooperation among network service providers." I sent this out to educate everyone and share the knowledge about how Google's Recursive DNS servers are setup for 8.8.8.8 / 8.8.4.4. Yes, some people already know how google handles their DNS service and have read the Google DNS FAQ page where this information is buried in the middle of the page. But if you never had to really troubleshoot in depth an issue with Google's DNS Server you probably never read that article. (https://developers.google.com/speed/public-dns/faq) We still get the email on the various lists whether it's Nanog or the Outages with the subject "OMG 8.8.8.8 IS DOWN!!!!" (Yes I admitted I was responsible for one of these email threads when we had the issues with Google DNS servers in the Atlanta Area a couple months ago). Then everyone starts responding with, mine works and I am in New York, London, Chicago, Dallas, and etc. And the original reporter of this issue has no idea why they are down and no one else is down to 8.8.8.8. At least this way someone might be able to take the troubleshooting step further and narrowing down the issue to a Google DNS Cluster or a Server in the cluster. Maybe giving a Google Network or DNS admin lurking on the forum some more information go off of, which might make them take a more serious look at the outage report. I also don’t run a blog or anything, but let's not forget our posts do get indexed by Google's search engines. And this thread is already the 3rd result for "Google DNS Cluster" which might help some lone network admin that is not apart of NANOG troubleshooting google dns issues. They might even open a more informative ticket with their service provider's NOC. Anyways I am just another network engineer running my little corner of this global experiment that we call the "Internet" sharing some knowledge. -Erik -----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Alejandro Acosta Sent: Wednesday, August 23, 2017 9:40 PM To: nanog@nanog.org Subject: Re: Google DNS --- Figuring out which DNS Cluster you are using Excellent, thanks for sharing. El 23/8/17 a las 4:09 p.m., Erik Sundberg escribió:
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" <<<<<<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.
________________________________ 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.
On Wed, 23 Aug 2017 20:09:49 +0000 Erik Sundberg <ESundberg@nitelusa.com> wrote:
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
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. -s
Shaun, Good catch!!! I would be nice if this was lowered to 1 second. #dig o-o.myaddr.l.google.com -t txt @8.8.4.4 ;; ANSWER SECTION: o-o.myaddr.l.google.com. 51 IN TXT "74.125.80.4" o-o.myaddr.l.google.com. 51 IN TXT "edns0-client-subnet 14.161.5.0/24" <<< Not my ip but someone from this IP did query this 9 seconds ago. -----Original Message----- From: Shaun [mailto:nanog@shat.net] Sent: Wednesday, August 23, 2017 11:21 PM To: Erik Sundberg Cc: nanog@nanog.org Subject: Re: Google DNS --- Figuring out which DNS Cluster you are using On Wed, 23 Aug 2017 20:09:49 +0000 Erik Sundberg <ESundberg@nitelusa.com> wrote:
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
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. -s ________________________________ 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.
participants (9)
-
Alejandro Acosta -
Bjørn Mork -
Christopher Morrow -
Erik Sundberg -
i mawsog -
Joe Hamelin -
Mark Andrews -
Shaun -
Stephane Bortzmeyer