Domain Authority Factors
There are several measurements of domain authority from the perspective of links: the QUALITY of links pointing to a domain, the QUANTITY of links, toolbar pagerank, domain rankings on search results and domain keyword relevance to the topic. Let’s look at how each can affect the value of a link to your website:
How quality of links that point to a domain affect a link that is pointed to your website.
Example: www.site1.com links to you. How is a link from www.site1.com to your site affected by other links that point to www.site1.com?
Trusted links to a domain that links to your site are very important. If domain X has 100 trusted links, then a link from X is more valuable than a link from Z that has 1000 trashy links. This is especially true for new websites, which have low trust profile and tend to sit in the supplemental index.
How quantity of links to a domain affect a link coming from that domain to your website.
Example: www.site1.com links to you. How is a link from www.site1.com to your site affected purely by the number of outside links that point to www.site1.com?
This depends in part on the quality of outside links. For example, if X has 1000 links and Y has 100 links, then a link from X is more valuable — if all of those links are of equal quality. If W has 1000 trashy links and Z has 50 quality links, then a link from Z is more valuable.
The game is about quality. Though paid directories still tend to work, their value is going down. I believe Google will soon completely eliminate their effect, or minimize it so much that it simply wouldn’t be worth pursuing.
How Toolbar pagerank of a domain affects a link coming from that domain.
Example: www.site1.com has PR 4. How does that affect a link that comes from www.site1.com to your website?
Toolbar pagerank is not a real measure of Google pagerank. We know that it’s delayed for at least three months and can be adjusted by Google without real effects on search rankings. Do not trust pagerank too much; focus on link analysis instead. It’s a good general measure, but Google may be skewing it to offset link buys.
How domain rankings on search results affect a link coming from that domain to your site.
Example: site1.com rank #4 for “widgets.” How valuable is the link to your website, which you want to rank for “widgets” or “purple widget”?
This factor is very influential. A domain ranking for your keyword has been determined by algorithms to be very valuable and worthwhile. If you want to rank for the same or similar terms, then a link from that domain is an influential vote.
Example 2: site1.com ranks #2 for “purple cow.” How valuable is the link from www.site1.com to your domain, which you want to rank for “purple widget”?
This is influential as long as the linking domain has high trust and authority. Topically unrelated links coming from trusted websites still pass ranking value. They indicate a vote by a linking website, and since the website is trusted, that trust is partially passed on to you.
How does relevance of keywords within linking domain name affect your site?
Example: www.widgets.com links to your site. How does that affect the link’s value if you want to rank for “purple wigets”?
There a lot of disagreement about this. It is a fact that many domains can rank for keywords completely unrelated to their name. Perfect examples are Wikipedia and About.com. Domain keyword relevance can help, but it is not the deciding factor. Website authority and trust far outweigh this value.
The less links a page linking to your website has, the more pagerank value is passed. If a page has a 100 pagerank value (example), and links to 4 other sites, then each site gets 25 points. If that same page has 20 links to other sites, than each site gets only 5 points.
The higher the PR of a page (or the more quality inbound links it has), and the less links there are on that page, the juicier your link is.
Quality of Outbound Links Coming from a Page That Links to Your Domain
Example: site.com links to your website as well as: Microsoft.com, bmw.com and imb.com. How does the quality of Microsoft.com, bmw.com and imb.com affect your link? Assuming you have a good site, of course.
If you link is sitting together with lnks to quality websites on a page (assuming the page itself has good trust and authority) it can be an indicator that you’re on the same level… it’s a cue, but it’s not likely to give you similar authority.
URL of Linking Page
Example: is there a difference between a link from:
As long as URL can be spidered and indexed, this parameter is not likely to affect the value. There are other indicators. If first and second URLs both have quality inbounds, why would search engines discriminate based only on link structure? There are plenty of good indicators that the second page is as valuable as the first one, hence a link from the second page is just as valuable as a link from the first one.
Problems arise when content management systems use session IDs, and create different URLs to the same content.
Do endings such as .html, .php, .asp and .pdf affect link quality?
PHP, ASP, HTML and other web language extensions do not have much weight on the link. Document formats such as PDF (.pdf) and Word (.doc) seem to have different weight. There are many other factors that affect those documents, such as the inbounds and content. If a PDF has 1000 inbounds, then a link from that PDF is obviously a powerful one.
Some SEOs state that .pdfs and .docs pass less link value, but you will have to test this one yourself.
How Do Page Edits Affect Link Value to Your Site?
Example: site.com has a link to your domain. The page from which the link comes is edited once per week. How does that affect link value?
This is affected by other factors such as the type of query and topic. A link from a static page that has not been updated in years, but has a powerful link profile, is highly valuable. On the other hand, a link from CNN.com from a page that gets updated frequently is just as valuable. It depends on the type of website from which the link is coming. This factor is rather unimportant.
Negative Link Factors
Google has implemented, and continues to implement, technology that detects paid links. It still does a bad job, but it may look at several factors that cue algorithms about links. Such factors may include the word “Sponsored” next to the links or completely irrelevant footer sitewide links. Once Google is alarmed, it may discount the link as paid and stop it from passing ranking value.
“…when we encounter a <FORM> element on a high-quality site, we might choose to do a small number of queries using the form. For text boxes, our computers automatically choose words from the site that has the form; for select menus, check boxes, and radio buttons on the form, we choose from among the values of the HTML. Having chosen the values for each input, we generate and then try to crawl URLs that correspond to a possible query a user may have made…”
Page Excluded in Robot.txt file
If a page is excluded in Robot.txt, it is no longer spidered or indexed, nor does it pass pagerank. Getting a link from a robot.txt excluded page is worthless in terms of SEO.
In the fifth article we finish the series with the basics of on-page SEO: title tags, H tags, body, domain name, image, meta tags and more.