Change in Root Domains Linking to Root Domain
This alert monitors the normalized (logarithmically-scaled) sum of all external root domains linking to the root domain of the source URL (Moz Documentation). Changes in MozRank can be associated with the change in the number of root domains linking to your root domain. Hypertext links are generally associated with an increase or decrease in the amount of authority passed to your website internally.
Increase in External Root Domains Linking to Root Domain
An increase in your MozRank has the potential to indicate you have received additional external root domains linking to your website that are passing authority to the Root Domain. This is a good indicator that your site is earning valuable authority, and will contribute to higher rankings.
Decrease in External Sub-Domains Linking to your Sub-Domain
If the external root domain links pointing to your root domain are decreasing, that typically indicates you are losing domain authority. If you see this number dropping, you should check your site for a recent drop in backlinks to your site. Consistent drops in MozRank from a loss of authoritative links to your root domain can be an early indicator of lost rankings.
Let’s hope you have recently garnered new authoritative external root domain links to your root domain, and that you see this number on a steady upward trend. It is important to note that Moz can trigger false positives for this alert if there was a recent index update on their end, which would have an impact on the MozRank of all sites in their index. If you see a big jump or drop, you should check to see if Moz updated their index before freaking out!