Google host names, Google global cache, Google host names google global cache – Google Networking Best Practices for Large Deployments User Manual
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Networking Best Practices for Large Deployments
The second column in the result set is the TTL for the records in seconds. Based on these
sample results, we can determine that the IPv4 addresses are valid for only about 2.5 minutes.
Google IPv4 addresses for specific hostnames are not static. For example, do not assume
mail.google.com will always be 74.125.225.245. If you need to configure your environment to
accept mail from Google for a mail gateway, include all of the subnets from the
_spf.google.com record per th
article.
It is not recommended to use Google’s IPv4 address space to permit access to Google (see
“Google Global Cache”); however, IPv4 addresses can be used to implement traffic redirection
and prioritization to the Internet knowing the implications of Google Global Cache (a
recommendation stated throughout this document). A more robust option to implement these
prioritizations can be Google’s hostnames (see “Google Host Names”).
Google Host Names
Google owns and operates a large amount of domains to serve the various services, products,
partnerships, and ventures in use. To efficiently serve and operate such a large, global Internet
presence requires advanced network engineering and optimizations. Therefore, any system
that uses Google’s hostnames should not be used as a means to allow access. Google
providing a static list of hostnames for use in customer networking configuration is impractical.
Rather, hostnames should be used to implement traffic redirection or prioritization to the
Internet; a recommendation stated throughout this document.
For a sample list of wildcarded hostnam
Note:
This list comes with no expressed warranty as to its accuracy at any given point in
time. It is merely a starting point for a network administrator and should be maintained
by the Enterprise going forward through log analysis.
Google Global Cache
Many of Google’s services and applications participate in the
content delivery system. The goal of this system is to provide the best service to all users by
deploying the knowledge and learnings from our Network Engineering teams.
The GGC system involves Network Operators and Internet Service Providers in the
distribution of commonly accessed resources. The participants in GGC have deployed a
number of Google owned and operated servers inside their network to serve popular Google
content. This results in IPv4 addresses being used with Google services and applications that
are owned by these host operators. Therefore, any use of Google’s IPv4 addresses to allow
access should not be used. Rather, IPv4 addresses may be used to implement traffic
redirection or prioritization knowing that there may be some Google related traffic going to
IPv4 addresses not listed.
Google’s use of GGC for content delivery is most effective for users with a large "network-
distance” from Google (
). Google’s use of GGC is dynamic in
both the services and client networks it applies to. Refer to the frequently asked questions at
for more information related to GGC and its use.