Does it still resolve to your site? If not, it should fall off as Google spiders it again.

Let's start with the first important question: Did I pay for this link? If the answer is "Yes", then do they nofollow the link? If no, you need to either get it removed or make sure they nofollow it.

So now we've gotten the obvious ones out of the way. Now... how to spot the unnatural links. A link can be unnatural if

• It shares specific keyword rich words with other links. For example you have 200 sites that link to you saying "Buy widgets now"
• The sites are low quality. Blogs with 1-3 posts that look abandoned after posting content that reads like an ad for you. Article writing sites.
• The site has no logical relation to your site whatsoever. Tire stores linking to doll stores doesn't make sense.
• There's a network of these links. If you've not gotten the hint from the previous two, look for patterns that stick out to you.
• There's little diversity. You have lots of links from very few sites.

So how to spot them? I'd cross-reference AHrefs with Open Site Explorer and look at keyword text and, in OSE, look at the strength of the site (PA/DA columns).

Lastly, what to do about them? If you think there's something that is actively hurting you then slowly begin to chip away at the links either by requesting removal or disavow. but remember that if you don't do this without a plan you WILL hurt your site.

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The only reason to use a fragment (the hashtag part of a URL is called a fragment) as your anchor, is that you're adding that link solely for the purpose of tying it to a DOM event (like an onclick event). There's better ways to do this in modern web programming, but it's still possible to see some old school sites doing

link

By definition, fragments exist solely for the client. Your web server will not log them. Google Analytics does not natively track them. So clicking on an empty fragment like that will just take you back to the top of your page (provided the JS doesn't stop the event). There's nothing to track. But there's something interesting to note here

link

Google can actually do some basic JS and it will recognize this bad attempt at link obfuscation as an actual link. So if you have links similar to this (which is not recommended) then those links will be counted as links. Be aware of this if you're worried about backlinks.

You won't get a referrer. Googlebot is not like a real user, surfing from site to site. What Googlebot does is this (more or less)

1. Googlebot requests a standalone page
2. Googlebot parses the page out. During this process it notes the links on that page and, depending on various mechanisms (nofollow, internal page rank, the mood of Matt Cutts, etc) it will note those links for the system to parse later
3. Googlebot is done so it grabs another page off the page list (likely without know how it got on said list) and goes back to #1

Now, to your question. Since Googlebot has no referrer it won't get your alternate content. This means that your alternate content page won't get indexed.

I would suggest here that a best practice is NOT to filter on referrer data, which can be inconsistent and potentially fake. Instead, I would make a separate page that contains your extra data and allow users to decide if they want more information Thus Googlebot finds all your content and your users get a better experience.

Except for geolocation purposes, your IP has no real effect on your SEO. The only thing I would suggest is making your TTL on your DNS records very low about a day before you move so when you do move you minimize the chance that you're hitting the old IP.

Not really. Google is looking for unnatural links and patterns. A single sitewide footer link isn't going to impact SEO that much. If the sites all share the same server/IP Google will likely just devalue them (not penalize) and move on. If you're still uncertain you can always nofollow them.

The only exception would be if you're trying to link targeted words in the anchor (which does look spammy). Just link the site names.

You could... but it would skew your GA. They would all appear to be from one user. You would have no meaningful metrics either.

The way to add them would be to code a page that generates the sales codes for GA then call it. That would transmit the data to Google.