Domain Authority (DA) is a Moz metric scored from 1 to 100 that predicts how well a site will rank in search results. You find it by plugging a domain into Moz's Link Explorer at moz.com/link-explorer or installing the free MozBar browser extension, which displays DA directly in your search results and on any page you visit. Moz gives you 10 free queries per month on Link Explorer without an account. For serious link prospecting, a Moz Pro subscription starts around $99 USD monthly and unlocks bulk checks and historical tracking. The MozBar extension remains free and works well for quick spot checks when evaluating potential link partners. If you use Ahrefs or Semrush, those platforms offer equivalent metrics called Domain Rating (DR) and Authority Score respectively. DR also runs 0–100 and correlates closely with DA in practice, though the underlying algorithms differ slightly. Ahrefs starts at roughly $129 USD monthly, Semrush around $139 USD. At Ottawa SEO we rely on Ahrefs DR for our 500+ domain portfolio because the index updates faster and the bulk analysis tools integrate better with our workflow. When evaluating link opportunities, remember DA and DR are comparative scores, not Google ranking factors. A DA 35 niche blog can outrank a DA 60 site for specific long-tail queries if the content and relevance are stronger. Focus on the trend rather than absolute numbers—a site climbing from DA 25 to DA 32 over six months shows momentum, while a stagnant DA 45 that hasn't earned new links in two years is likely declining in real authority. For Canadian link building, check DA on regional directories, local news sites, and .ca domains in your niche. A DA 28 Ottawa Business Journal backlink often delivers more qualified traffic than a DA 50 generic guest post on an offshore content farm. Prioritize relevance and editorial standards over raw DA scores, but use the metric to avoid wasting outreach on completely untrusted domains below DA 10–15.