Welcome to WebmasterWorld Guest from 18.104.22.168
I moved to a new server and then all my rankings are GONE! So this makes me wonder if it's:
1. a change in the algorithm that filtered my site, or
2. Google now sees this as a whole new website and thus places it in the dreaded sandbox?
I don't have a robots.txt file, and I didn't have one before the move.
I moved the site about 2-3 weeks ago. When I saw that my rankings were gone, I resubmitted the site to Google this week, just in case...
How do I know if I got filtered out, or if I just need to have some patience before I come back into the SERPs?
Google caches DNS lookups. That is, they have cached the old IP address for the site's domain, and will use that for awhile.
Some hosts will re-populate servers on evacuated IP addresses with a default boilerplate "Coming soon" page. (This is a simplification of what they really do, but it's accurate enough for this discussion.)
So, if you didn't leave your old site up on the old server until Google started spidering the new one, then they may be indexing that "Coming soon" page until their DNS cache expires. Although this should happen fairly soon, it's better to avoid this situation.
Always leave your belongings in your old house until you're completely finished cleaning and re-painting the new one... Even if it means paying an extra month's fees.