Domain Authority is Moz's proprietary metric that scores websites from 1 to 100 based on their predicted ranking ability. Higher scores indicate stronger link profiles and better potential to rank. The score uses a machine learning model trained against Google search results, pulling data from Moz's own Link Explorer index—not Google's actual algorithm. Moz calculates DA primarily from backlink signals: total linking root domains, total links, and the quality of those linking sites measured by their own DA scores. It's logarithmic, so jumping from 20 to 30 is easier than 70 to 80. A brand-new site starts near zero, while established news sites or university domains often sit in the 80–95 range. Most small business sites we audit in Ottawa land between 15 and 40, competitive e-commerce sites in the 40–60 range. Google doesn't use DA. They have their own internal metrics. DA is a third-party estimate that correlates with ranking potential but doesn't cause rankings. We see clients obsess over DA when they should focus on relevance—a backlink from a DA 35 industry blog often outperforms a DA 60 generic directory because topical authority matters more than the number itself. DA updates roughly monthly when Moz recalculates their index. Scores can drop even when your links stay the same, because competitors gained links or Moz adjusted their model. That's normal. Don't panic over a 3-point swing. We use DA at Ottawa SEO for quick competitor comparisons and vetting outreach targets. If we're pitching a guest post, we'll check DA to confirm the site has legitimate authority, but we prioritize traffic estimates and topical relevance first. A DA 28 niche blog with engaged readers beats a DA 55 link farm every time. For link building, aim to earn backlinks from sites with DA equal to or higher than yours. If you're at DA 22, landing links from DA 30–50 sites moves the needle. Chasing DA 90 outlets when you're starting out wastes time—they won't link to you, and one DA 35 relevant link does more than ten DA 15 spammy ones.