Hi there, Sorry if this is in the wrong forum section but... I have just seen my keyword phrase drop and then go back up and then drop again. On checking the datacentre that I am currently viewng (through Firefox with SHOWIP addon) I see that it is currently top on most of the subdomains but not the IP I am currently viewing! My questions is... how often does Google change the IP of the data centre that I am viewing?
This seems impossible to understand. What subdomains? What exactly are you saying? Again, hard to make sense of what you are saying. Google doesn't change the IPs of its datacenters. Are you perhaps asking how often you will be hitting a different datacenter when you search? If so, no one (outside Google) knows that. But it's possible that your result is jumping around within the same datacenter, or perhaps you are checking from different computers or browsers, and on one of them search personalization is kicking in. Impossible to say without clear / complete info. If you want to check your results across multiple datacenters, use this tool (the best of its kind): http://www.seocritique.com/datacentertool/
It could be your site and the key phrase or data center in on google dance activity that makes that fluctuation of the rankings. It's normal and would back to regular serp result in few days, and getting strong backlinks could secure your site on good position.
This is not about Google changing their IP but it is about your website ranking fluctuation. You should not panic and keep watching instead. This is a sign of unstable ranking from not having enough quality backlinks and not enough trust toward your domain as well.