Ok so I'm finally tired of the downtime at my current host, so I'll be changing real soon. What's the best way to change so google doesn't think my site is gone? I'm sure once I change my name servers eventually google will pick it up.. but how long before they update their cache?
Is there anything I should put in the robots.txt or .htaccess on my old site so google will automatically look for the new ip address or new site if they hit the old hosting company?
Hey Terry, Ive worked with loads of companies who change servers a number of times...short answer, dont worry about it. Changing servers isnt an issue at all...as long as your site isnt down for days and days then theres no worry there trust me.
As for the cashing, see if you can leave your old site up and running for 72 hours so the images, scripts, etc can still be served from location they are requested.
If your domain name hasn't changed, then the DNS will do all the work and all the proxies and IPs should point to the new location within that 72 hour period of time. Then you can take down the old site. But as SuzziJ said, it's really not a big issue with Google or any other SE to my knowledge.
You should always make sure that you see Googlebot on your NEW IP before you cancel hosting with your old IP. Googlebot doesn't check that the IP address is the one you are currently using it when it comes by, so it might not realize that you have moved right away. This will save you from dropping from the index (even temporarily) because Googlebot can't find the site on your old IP, and hasn't realized your site is on a new IP address while they update the nameservers.
Paying an extra month of hosting is worth the piece of mind :)