# How do websites with multiple data centers work? **URL:** \ **Category:** Factual Questions\ **Created:** [May 25, 2011, 8:32pm UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201 "2011-05-25T20:32:26Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![treis](https://avatars.discourse-cdn.com/v4/letter/t/bc79bd/32.png) [@treis](https://boards.straightdope.com/u/treis)\ **Post date:** [May 25, 2011, 8:32pm UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/1 "2011-05-25T20:32:26Z")
Take, for example, Google. They have a ton of data centers around the world, which I assume handle the traffic for that region. For example, if I am in Athens and go to [google.com](http://google.com), I assume that my request doesn’t go all the way to San Francisco. I assume that it goes to a datacenter somewhere in Europe that Google owns. Is that right? If so, how does that work in terms of routing? Do the backbones of Europe have a different listing for [Google.com](http://Google.com) than those of the USA? ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [May 25, 2011, 8:38pm UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/2 "2011-05-25T20:38:04Z")
the subdomian ([www.google.com](http://www.google.com)) is translated into an IP address by what is termed a name server, that IP address is what the internet uses to route your request to google’s servers. Some name servers do change the response they give based on your location. Some also give multiple answers and the clients grab one of those answers at random. So it really depends and is under the control of the person who owns the domain. I am overly simplifying so please let me know if you want a more in depth answer. ---
**Author:** ![treis](https://avatars.discourse-cdn.com/v4/letter/t/bc79bd/32.png) [@treis](https://boards.straightdope.com/u/treis)\ **Post date:** [May 25, 2011, 8:42pm UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/3 "2011-05-25T20:42:52Z")
So it’s basically controlled by my ISP or whoever runs the DNS server that my ISP uses? I assume then that there is some guy at each DNS that I can call up and request to have a different IP number assigned to my domain name? ETA: I thought DNS servers were linked as well. In that, an authorized change in one with propagate through the system. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [May 25, 2011, 8:48pm UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/4 "2011-05-25T20:48:02Z")
No it is controlled by the DNS server for the domain you are trying to reach. DNS servers work on a referral system, there are a limited number of “master” servers who know who is the authorized DNS server for every domain, your ISP’s DNS server will ask those root servers who to ask to find out where to find the destination subdomain. If you have a domain name the registrar you registered the domain with will be the ones who report the servers to ask for your DNS servers. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [May 25, 2011, 8:55pm UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/5 "2011-05-25T20:55:20Z")
I should also say that it gets a lot more complicated than just DNS. Sometimes the same IP can be used world wide and through using the paths that the IP traffic follows they can have that IP address go to different Data centers based on the source. Once again, a gross oversimplification. ---
**Author:** ![Ruminator](https://avatars.discourse-cdn.com/v4/letter/r/b9bd4f/32.png) [@Ruminator](https://boards.straightdope.com/u/Ruminator)\ **Post date:** [May 25, 2011, 9:10pm UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/6 "2011-05-25T21:10:41Z")
> [@treis](#): > > If so, how does that work in terms of routing? Do the backbones of Europe have a different listing for [Google.com](http://Google.com) than those of the USA? Here’s a short article that may help: [http://www.royans.net/arch/fixing-gslb-global-server-load-balancing/](http://www.royans.net/arch/fixing-gslb-global-server-load-balancing/) It’s too short to give you all the answers you’re looking for but maybe it will help add some terminology so you can structure your next set of questions. ---
**Author:** ![Markxxx](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@Markxxx](https://boards.straightdope.com/u/Markxxx)\ **Post date:** [May 26, 2011, 1:46am UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/7 "2011-05-26T01:46:13Z")
Google has lots of data centers. In fact you can be #1 on one data center and #6 on another and #10 on yet another. This is why there are tools that let you compare how well your site comes up in different Google data centers. Every so often Google syncs the various centers and makes the results uniform. When I did SEO it really bothered my clients are they were like "How come sometimes I’m #1, then I’m #4 then, #1 again. I’d show them [Google.Com](http://Google.Com) goes to different IP addresses and it depends on which Google IP it goes to as well as if they data centers are synced up. ---
**Author:** ![Terry\_Kennedy](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@Terry\_Kennedy](https://boards.straightdope.com/u/Terry_Kennedy)\ **Post date:** [May 26, 2011, 2:01am UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/8 "2011-05-26T02:01:02Z")
> [@rat\_avatar](#): > > DNS servers work on a referral system, there are a limited number of “master” servers who know who is the authorized DNS server for every domain, your ISP’s DNS server will ask those root servers who to ask to find out where to find the destination subdomain. There’s also the special case of the F-root, which is a root name server that appears in slightly less than 50 places world-wide. You can read more about it [here](http://www.isc.org/community/f-root) and [here](http://www.isc.org/community/blog/201008/f-root-routing-how-does-it-work-0), and more about the general concept in [this](http://en.wikipedia.org/wiki/Anycast) Wikipedia article. F-root’s - they’re everywhere: ```auto gw1.nycmnycz>traceroute f.root-servers.net Translating "f.root-servers.net"...domain server (10.0.0.146) [OK] Type escape sequence to abort. Tracing the route to f.root-servers.net (192.5.5.241) 1 nyiix1.lga1.isc.org (69.48.130.115) 0 msec 0 msec 0 msec 2 f.root-servers.net (192.5.5.241) [AS 3557] 0 msec 0 msec 0 msec ``` ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [May 26, 2011, 2:11pm UTC](https://boards.straightdope.com/t/how-do-websites-with-multiple-data-centers-work/583201/9 "2011-05-26T14:11:49Z")
For Google specifically there are also country-specific urls. e.g. [www.google.com](http://www.google.com) is the USA & “universal” url. But they also have www.google.co.nz in New Zealand. And if you’re in NZ and type “[www.google.com](http://www.google.com)” into your browser, you’ll be redirected to www.google.co.nz which will then serve up the familiar search page. Many other multi-national firms have local websites in local datacenters using distinct local urls.