Leosghost - 6:46 pm on Apr 20, 2012 (gmt 0)
<slightly OT> apologies to Brinked :)..not "hi-jacking" here ..
To reinforce brinked's point re sites on same server ( same IP ) this happened to me in the last 7 days..
For around 8 years I have had a small number ( of the many sites I now run ) on a shared account,( each relatively undeveloped, but each featuring very well in serps for their own various keywords..and always at #1 for their own names )..these are all EMD or distinctive , short, memorable names..<= I like these sort of names :)
So much for the background..
Last weekend ..all of them vanished..
For all keywords, and each was also "gone" for their own names..the only mention of them was in the various "whois" sites ..
De-indexed..( and I hadn't touched any of them in at least a year ) ..punished ..shunned by Google..
So I checked the IP..
( remember it was a shared account..one of many such places and shared Ips, where I "park" domains before putting them on their own server or own IP when I get around to fleshing them out or promoting them..so most of the other domains on these IPs are not mine )
All the other sites on the same IP were also gone..de-indexed..only trace or mention of them was in the various "whois" ..
So the IP was de-indexed...over 200 sites ..gone..
The last time I had checked my rankings was the previous day..only takes me 5 minutes, and I do it daily ..so I caught this..G had crawled them the previous day..
I moved all mine to their own IP..they were "re housed" within 12 hours of the de-indexing of their old IP..
G crawled again ( with them on the new IP ) 3 hours later..and 1 hour later ..they were all back..previous rankings all in place..:)
I have checked the other sites on the old IP, they are still gone, someone in the bunch has done something that caused Google to remove all of us, I've spoken with the host company ( one of the most well known and reputable ), they were unaware of this having happened,( although they had heard of the phenomena, but never seen it ) but they checked, and confirmed my findings..
The others on the old IP are de-indexed..
I haven't seen G do this in a long time, and it may be a "bug"..but it is a bug that is still affecting the other sites on that old IP 5 days on..and they do not all have the same owner..
Nor are they at all similar in their subjects or contents or targets..but they were all found "guilty by association" of being on the same IP ..
It might never happen to you..but...
I now have all my sites ( those which are not actually parked with commercial parking ) , whatever stage of development they are in, on IPs that only I use..and they are all well spread out across various hosters servers and countries..buying dedicated IPs is cheap , fast and easy, I spent a day and a few hundred dollars ..worth the trouble, should have tied up these "loose ends" before..but got distracted and forgot to get around to some of them..
Once bitten..even lightly and briefly..lesson learned..