Domain Authority is Moz's attempt to model Google's view of a site's overall ranking potential. The score correlates strongly with actual search performance across large datasets, which is why SEO agencies use it as a quick proxy for comparing link opportunities or portfolio site strength. A DA of 30 might represent a decent local business site, 50–60 is competitive regional presence, and 70+ typically means national authority or major publishers. Ottawa SEO Inc. tracks DA across our 500+ domain portfolio, but we never optimize for DA itself—it's a reflection of link building work, not a target. The calculation weighs linking root domains heavily, prioritizes links from high-authority sources, and penalizes spammy patterns. Moz updates the metric periodically, sometimes causing fluctuations unrelated to your actual link profile. When a sitewide recalculation happens, 20–30% of domains might shift 5–10 points simply due to model changes. This is normal algorithmic drift, not real-world impact. DA matters most for prioritization decisions. If you earn a guest post opportunity on a DA 45 site versus a DA 22 site in the same niche, the former usually passes more equity and relevance signals. But context always trumps the number—a DA 28 industry trade publication often beats a DA 55 general blog for B2B clients. We've seen Ottawa clients rank competitively in professional services verticals with DA in the mid-30s because their backlink profiles matched search intent better than higher-DA competitors chasing volume. Common mistakes include obsessing over small DA movements or buying links solely based on DA without vetting traffic, relevance, or link placement. Domain Authority also doesn't account for penalties, manual actions, or recent algorithm updates until Moz's next index refresh. For Canadian agencies working with CRA-regulated industries or local service areas, a DA 40 site with strong geo-targeting and topical authority outperforms a DA 60 clickbait domain every time. Use DA as one signal in a broader link quality assessment, not as the sole decision filter.