I keep seeing people refer to a random rag-bag collection of IP addresses that bring up the "Google English" search box, and then refer to those as being from "56 Google DataCentres". I assumed that Google would be more organised than that, and always felt that there must have been an expansion in the number of IPs brought into use since the time that most of the Google IP address lists were compiled back in 2004. So I went looking...
You're probably aware that a few weeks ago I uncovered another 500 IP addresses that also bring up that search box, taking the total to well over 600 IPs that are active. The list is featured in several places including Search Engines Forums which is the original place that I posted it in.
Many years ago, Google had a collection of addresses like www.sj.google.com etc that brought a search box up. There were many others (-fi, -in, -va, -ab, -dc, -cw, -ex, -zu, -sj, -lm, -mc, -kr, -gv, etc). They retired those names in 2004 forcing everyone to refer to results using the bare IP address.
Whenever you access a search result at www.google.com you get your result from a random Google IP address. Usually that IP address ends in x.x.x.104 or x.x.x.99 or x.x.x.147 and the cache comes from the same Class-C IP block.
Much confusion has ensued as Google has many hundreds of IPs that never seem to directly serve results. As well as IP addresses ending in 99, 104, and 147, they also have some ending in 44, 80, 91, 115, 184, 214, and many others for example.
Whenever you look at which Class-C block that is serving the results, you seem to get a different one every few minutes, but over the course of a few weeks you might have seen only 7 or 8 different ones. But we now know that Google actually has 41 such blocks.
So, there are several dozen Class-C blocks that don't seem to make it into the rotation either.
Well, today, I found the missing link to all of this and I think I can confirm that Google has 41 datacentres, each spanning a single Class-C block, and that the www-xx.google.com URLs weren't actually retired back in 2004 after all.
In fact, they were merely renamed to a new gfe-xx.google.com format and many retained the old two letter ID pair from the old www-xx style names too.
I have found 41 such names and they correspond to each of the recently known 41 Class-C IP blocks that Google uses to serve results.
Each gfe-xx.google.com name serves results from an IP address ending x.x.x.104.
Additionally, for some of the gfe-xx.google.com names, there are extra entries at gfe-xx2.google.com that serves results from the same Class-C block but with an IP address ending x.x.x.99 and for some there is yet another entry at gfe-xx3.google.com that serves results from an IP like x.x.x.147 but again this comes from the same Class-C block.
More can be found at this thread where all the Class-C blocks are listed, along with their newly found "gfe" names, and range of IPs that respond.
And GFE, what does it stand for? Google Fools Everyone?
If you're a "Google Toolmaker" I hope this post hasn't given you a heart attack.