In August, my client's site (I work at a marketing agency) had about 15,000 backlinks. Now they suddenly have about 10,000 backlinks. And their Domain Authority has dropped from 48 to 40! Can someone please help me understand what could've happened? At first I assumed this had something to do with the latest Penguin update, since I knew my client's site had some extremely spammy backlinks they hadn't cleaned up yet. (The site was hacked at some point and hidden pages were created as part of some kind of link-building scheme, and there were lots of links from sketchy sites to those pages. The hidden pages have been taken down and the URLs now redirect to my client's home page.) But that would only explain a sudden drop in Domain Authority, right? How could Penguin suddenly cause my client to lose 5,000 backlinks? And if it's not Penguin, what could it be? Thanks in advance for any insight that anyone can share!

I've got a site with two versions – a U.S. version and a European version. Users are directed to the appropriate version through a landing page that asks where they're located; both sites are on the same domain, except one is .com/us and the other is .com/eu. My issue is that for some keywords, the European version is outranking the U.S. version in Google's U.S. SERPs. Not only that, but when Google displays sitelinks in the U.S. SERPs, it's a combination of pages on the European site and the U.S. site. Does anyone know how I can stop the European site from outranking the U.S. site in the U.S.? Or how I can get Google to only display sitelinks for pages on the U.S. site in the U.S. SERPs? Thanks in advance for any light you can shed on this topic!

My boss has asked me to track the number of searches for a keyword (a particular company's name) on a daily basis this week to see how the volume fluctuates from day to day. Is this even possible? I should note that his request does not involve an active SEO or AdWords campaign. In fact, the company my boss is interested in doesn't even have a website at the moment. Thanks in advance – either for helping me confirm that it's impossible to track keyword search volume on a day-to-day basis, or for showing me the magical way to actually do this.

Someone told me that having a URL that ends in .net (instead of .com) will hurt my site's SEO. Is that true?