Here are a few reasons why your DR may have dropped. 

1: Other sites did a better job on linkbuilding 

If you didn't lose any backlinks, and yet your DR still dropped, this could be a reason. 

Think of it this way: when a DR‐100 website gets more backlinks, we can’t make it DR‐101. So instead we push all the other websites down by 1. 

That’s a very raw explanation of why you might see a drop in your DR while no backlinks were lost.

2: You are losing high-quality dofollow links 

Domain Rating shows the strength of a given website’s overall backlink profile. It's measured on a logarithmic scale from 1 to 100, with the latter being the strongest.

That means that your DR will drop if you're beginning to lose high-quality links. 

Do check your "Lost Referring Domains" report to investigate what domains with dofollow links you lost at the time of decline and see if you can fix it.

3:  Some dofollow link from any of referring domains turned to nofollow and that domain stopped passing rating

4:  Some of referring domains lost rating itself

Note: If there is a change in our crawl algorithm, please be assured that we will definitely inform you. 

Note: Please, mind that Ahrefs Rank (AR) is based on Domain Rating (DR), so reasons for decline of DR explained above apply to those of AR decline respectively.

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