Rustybrick at SEOroundtable has drawn attention to a very interesting thread which should make those in charge of client webservers prick up their ears. I encounter resistance from some clients when I suggest a hosting change once I see they’re using a cut-rate provider. DNS changes, server switch-overs, and broken 404 pages are all major poison to your Google rank. It’s also sounding like you may not get back where you were in the Google index – as it’s my understanding that Google counts “length in index” as one of its 200 ranking factors.
People wonder sometimes why I run my own servers and have a backup SLA of 4-6 hours. I think his observation speaks directly to the need for this. SEO and server uptime are peas in a pod, folks.
So the next time your host says “your site will be off-line for a few hours while we do maintenence” think about the implications to your rank!