Whenever we are at trade shows, run seminars, or speak at symposiums we get asked the question "what is the Google dance?" We've heard a few different things referred to as "the Google Dance", but only one is really correct. It's the period when Google is rebuilding its rankings, and results fluctuate widely for a 3 to 5 day period.
How Often Does The Google Dance Happen?
The name "Google Dance" was in the past used to describe the period that a major index update of the Google search engine are being implemented. These major Google index update occured on average every 36 days or 10 times per year. It was easiest be identified by significant changes in search results, and by an updating of Google's cache of all indexed pages. These changes would be evident from one minute to the next. But the update did not proceed as a switch from one index to another like the flip of a switch. In fact, it took several days to finish the complete update of the index.
Because Google, like every other search engine, depends on their customers knowing that they deliver authoritative reliable results 24 hours of the day, seven days a week, updates pose a serious issue. They can not shut down for maintenance and they cannot afford to go offline for even one minute. Hence, we had the Dance. Every search engine goes through it, some more or less often than Google. However, it is only because of Google's reach that we pay attention to its rebuild more than that of any other engine.
Since August 2003, the famous / infamous Google Dance is no more. Or rather it has become less dramatic. Google now performs updates every week, with most movement occurring on Mondays. These ongoing updates feature mostly minor algorithm and index updates.
So, during any month there will be minor changes in rankings. This is because Google's bot or spider is always running and finding new material. It also happens because the bot may have detected that a website no longer exists, and needs to be deleted from the index. During the Dance, the Googlebot will revisit every website, figure out how many sites link to it, and how many it links out to, and how valuable these links are.
Because Google is constantly crawling and updated selected pages, their search results will vary slightly over the course of the month. However, it is only during the Google Dance that these results can swing wildly. You also need to consider that Google has multiple data centers, sharing more than 10,000 servers. Somehow, the updates to the index that occur during the month, and outside of the Google Dance have to get transferred throughout. It's a constant process for Google, and every other search engine. These ongoing, incremental updates only affect parts of the index at any one time.
Checking The Google Dance
Until January 2004, Google had 12 main www servers online, which were as follows:
* www-ex.google.com - (where you get when you type www.google.com)
* www-sj.google.com - (which can also be accessed at www2.google.com)
* www-va.google.com - (which can also be accessed at www3.google.com)
* www-dc.google.com
* www-ab.google.com
* www-in.google.com
* www-zu.google.com
* www-cw.google.com
* www-fi.google.com - found in May 2003.
* www-gv.google.com - found in August 2003.
* www-gv2.google.com - found in September 2003.
* www-kr.google.com - found in October 2003.
At some point in January, these servers stopped accepting connections, and the only servers easy to connect to were:
* www.google.com
* www2.google.com
* www3.google.com
As well as the numeric address databases - which people keep discovering, and kindly help us keep abreast of.
* 216.239.37.99
* 216.239.39.99
* 216.239.41.99
* 216.239.51.99
* 216.239.37.104
* 216.239.41.104
* 216.239.37.147
* 64.233.161.98
* 64.233.161.99
* 64.233.161.104
* 64.233.161.105
At any time during an index update you can check the Google servers, and they will display sometime wildly differing results, thus they are said to be "dancing", and hence the name "Google Dance".
In the past, the easiest way to check if the Google Dance was happening was to go to www.google.com, and do a search. Look at the blue bar at the top of the page. It would have the words "Results 1 - 10 of about 626,000. Search took 0.48 seconds" Then check the same search on www2.google.com, and www3.google.com. If you were seeing a different number of total pages for the same search, then the Google Dance was on. You could also check all the variations above. www2 is really www-sj, and www3 is www-va. We have found that all the others need their full www-extension.google.com in the url if you want to test them properly. Once the numbers, and the order of results on all 10 www's are the same, you knew the dance is over.
Importance Of The Google Dance
For most people, this event in and of itself was not important. However for anyone in the search engine optimization industry it was a period of note. Pages got temporarily dropped. Sometimes it lasted a day. People panicked. Then they are re-added, and they are better placed than before, and things calmed down. It's interesting to see how overpoweringly important this one engine is. For more information on about this search engine, or any other, please read our sections on The Search Engines.