Analysis of 1 Million Backlinks: Udemy (Part 1/10)

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Analysis of 1 Million Backlinks - Udemy

We analyzed 1 million backlinks via 10 random sample sets of 100,000 backlinks across 10 different websites from a variety of business verticals to determine how the link metrics from those backlinks would impact gains or losses in organic search visibility.

A Quick Word About Link Analysis at Scale

The goal is not to manually review each individual referring URL one by one. That would suck! I don’t know any SEOs who wake up in the morning and look forward to doing a task of such absurdity.

However, a more realistic goal is to look for patterns, trends and commonalities among link metrics for a given URL to determine whether or not it’s an unnatural link.

P.S. – Powerful crawlers and anchor text classifiers like URL profiler can literally save you hundreds of hours of grunt work. We’re in no way, shape or form affiliated with them, but we highly recommend checking them out!

URL Profiler

Upon completing a link audit, you should have a few outputs to work with:

  • Danger List – These are the links that are extremely likely to be unnatural and should be considered for disavowal.
  • Caution List – These are the links that could be unnatural and must be manually audited to determine if they are safe or dangerous.
  • Safe List – These are trustworthy, authoritative links that are most likely to be natural. Getting more of these will help boost organic visibility.
  • Link Schemes – These are large groups of similar links that are coming from the same source and are the most probable cause of site-wide links.
  • Link Opportunities – Some websites (especially popular brands) earn natural, high-quality links without knowing it. An audit will help you discover those sources so you can build relationships and earn more links.
  • Link Equity Consolidation – In almost every case, there are authoritative inbound links pointing to 404 pages on any given website. Those 404 pages should be revived by implementing 301 redirects to a live final destination URL to reclaim the lost link equity.

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Link Metrics Considered

The link metrics can be segmented into 4 key categories:

  • Diversity
  • Trust
  • Authority
  • Relevance

These are the primary link metrics that will be used to evaluate Udemy’s backlink profile:

Majestic Citation Flow – Rates how influential a URL may be based on how many sites are linking to it, and based on a 100-point scale.

Majestic Trust Flow – Predicts how trustworthy a page is based on the trustworthiness of those sites that are linking to it, based on a 100-point scale.

Moz Spam Score – Rates the level of penalization risk associated with a given URL, based on a scale of 0 – 17 where any rating of 11 or higher is likely to be spam.

Moz Domain Authority – An overall website rating that is calculated by metrics, such as linking domains, number of total links, MozRank, MozTrust, into a single 100-point logarithmic score.

Ahrefs Referring IP C-Class Diversity – IP Addresses are divided into lettered blocks (AAA.BBB.CCC.DDD). The more referring C-Class Duplicates that exist within the link profile indicates that the site is likely to be engaging in link networking.

Ahrefs URL Rating – Prediction score for how well a page is likely to rank in organic search results, based on a 0-100 scale.

Learn More: What Is Link Roundup Link Building: The Practical Guide

Domains Evaluated

We included the following 10 websites in our study:

Analysis of 1 Million Backlinks - Udemy

Analysis of 1 Million Backlinks: Udemy

Udemy is an online learning and teaching marketplace with over 42,000 courses and 14 million students. With Udemy, you can learn programming, marketing, data science and more – all at your own pace and schedule.

Udemy

Key Insights: Udemy’s Link Profile

  • Referring Domain Velocity: Udemy has built links from more referring domains over time than key competitors. On average, they earn links from approximately 2,000 referring domains per month. That level of referring domain growth has been instrumental to their organic search visibility. 

Analysis of 1 Million Backlinks - Udemy

Source: Majestic

  • Sitewide Linking: The most unnatural link type detected on Udemy’s link profile was sitewide links. A sizeable portion of those links were widget links. A referring domain to backlink ratio of approximately 94:1 is a cause for concern.

Analysis of 1 Million Backlinks - Udemy  Source: Ahrefs

Ahrefs reveals that EFLClassroom is linking to Udemy over 400k times:

Analysis of 1 Million Backlinks - Udemy

Google calls out that the site is likely hacked and the meta description clearly states that it's a directory link website. This is a strong indicator of low-quality links:

Analysis of 1 Million Backlinks - Udemy

Clear sign of an untrustworthy website that lacks brand credibility. Not the type of website you want 400,000 backlinks from.

Analysis of 1 Million Backlinks - Udemy

After data sterilization, approximately 48,000 live links were found:

Analysis of 1 Million Backlinks - Udemy

The distribution is showing that most referring domains have an authority of 30 or less, however there are a few outliers at DA 30 and DA 90:

Analysis of 1 Million Backlinks - Udemy

Outlier at DA 30 – Newmarksdoor.comThis is your typical DA 30 blog. Upon reviewing the site, it looks pretty safe. But let’s see where all those links are coming from.

Analysis of 1 Million Backlinks - Udemy

Well I’ll be darned. It’s a sidebar widget link embedded into the template of every page on the site. This is the type of link that could potentially get you into trouble, especially given that Google recently issued a warning on sitewide widget links.

This could be perceived as unnatural linking at some point, so I’d recommend that Udemy ask them to implement a rel=nofollow attribute to remain on the safe side.

Normally this may not be worth Udemy’s time, but because there are so many incoming widget links, it would behoove them to nip this potential problem in the bud. The referring URL level distribution tells us that most links are of low authority; however, there appears to be an outlier at URL Rating 7:

Analysis of 1 Million Backlinks - Udemy

This site that is loaded with strange links was the source of the URL Rating 7 outlier:

Analysis of 1 Million Backlinks - Udemy

The normalized distribution proves that most referring domains have a Trust Flow rating of zero. The drop-off after zero is pretty significant, which means that the majority of referring domains are not trustworthy:

Analysis of 1 Million Backlinks - Udemy

The URL Citation Flow is showing a drop-off that is slightly less intense than the Domain Trust Flow. We can still conclude that the vast majority of these referring links are not influential, and very few of them are positively impacting Udemy:

Analysis of 1 Million Backlinks - Udemy

Example of a link from an untrustworthy source:

Analysis of 1 Million Backlinks - Udemy

Moz’s Spam Score (0-17 scale) recommends reviewing links with a score above 10:

Analysis of 1 Million Backlinks - Udemy

Here’s a good example of classic link spam – just a list of links from a foreign TLD:

Analysis of 1 Million Backlinks - Udemy

Upon reviewing Moz’s Spam report, I noticed a huge number of .org links with a score of 11. Those links are collegiate rip-off sites, posing as affiliates and trying to steal leads:

Analysis of 1 Million Backlinks - Udemy

The site’s footer tells us everything we need to know:

Analysis of 1 Million Backlinks - Udemy

The Duplicate IP C-Class is a staggering 96%, which is a cause for further investigation:

Analysis of 1 Million Backlinks - Udemy

An example of low-quality links from different referring domains all hosted on the same IP C-Class. This is commonly known as a “link network”:

Analysis of 1 Million Backlinks - Udemy

These are the most commonly used phrases that external sites use when linking to Udemy:

Analysis of 1 Million Backlinks - Udemy

Most of Udemy’s backlinks are coming from content and blog posts:

Analysis of 1 Million Backlinks - Udemy

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