On WebmasterWorld, a member reported that some two weeks back he noticed a lower traffic for the USA IP range. After some digging he found that his site which in December was in top 10 now ranked somewhere around 60 on the USA Google data centers. However, it still ranked in top 10 in all other countries around the world for the same search terms.
This problem seem to have cropped up only a few weeks back and has affected several sites in the top 10 position. Also, many of the sites have lost their positions for the USA data centers. Further after some research he found that when he does a search on Google's main site, the result position is 50. However, through a ping test he found the 188.8.131.52 IP address. Later when he used searched directly using, bingo! his site was once again in top 10. But then again when he used, alas! He was back to the 50+ position. Thus the results on the same data center differ depending on whether you access it by IP or by domain name.
The discussion is still raging on the forum and with so many people sharing the problem, it certainly is not a rumor. But like always, among all the speculations and reasons, the real cause seems to be as elusive as ever. Can we Google it?