Hi , could someone tell me what the IP is in the google cahce url e.g

http://66.249.93.104/search?q=cache:...en&lr=&strip=1

this is the google cache url - is the IP at the beginning the IP of the data center , pages location etc??? I do searches on different PC's and on one search we rank 19th for a keyword and for the same keyword on a different PC we rank 59th?

I dont understand why google is throwing completely diffreent results at us, just becasue we are on different PC's? this seems to happen for most of our keywords? we get different results all the time from pc to pc?

The IP in the URL is the datacentre that answered your query.

Different datacentres can have different results, You can even get different results from the same datacentre as the DC can have several machine clusters that may answer the query.

It's all down to the continuous synchronising process and load balancing/sharing and multiple redundancy systems that Google have in place to ensure that queries are handled quickly and efficiently.

It does not depend on your location, it depends on how busy the cluster of DCs that are currently serving the query, sometimes you can requery on the same machine and see different results.

This is why you will find the more experienced SEOs will pretty much ignore rankings as a metric for the success of any campaign.
What is more important is the improvement in sales/conversions and/or visitors and the ROI for the client.
Any numpty could get a website to be No 1 in every search engine for some obscure phrase. If it brings no traffic what use is it ???

How do you explain to a client when they look, their site is on page 95 but on your machine it's on page 1 and you have sent them a ranking report.

I don't even bother to send ranking reports anymore. I just tell them to look at their site stats (which I provide all my clients) and they can see where the traffic is coming from themselves. Or, in some cases, I send them a monthly site traffic report from my server that covers everything.

I also track the various forms of lead and sale generation: any form-to-email that goes through a site I built sends a BCC to me, just so I know what's up.

That avoids the whole issue of "my site doesn't rank under X phrase" or "why can't I find it under ... "? (As long as someone does, that's all that matters.)