Domain Authority is a third-party metric created by Moz that predicts how well a site might rank in Google search results. It runs from 1 to 100, calculated from factors like linking root domains, total links, and MozRank. Google doesn't use DA in its algorithm at all—it's purely a tool for SEOs to compare sites and prioritize outreach targets. Where DA is useful: when you're vetting link opportunities, a DA 60 site is generally stronger than a DA 25 site, assuming relevance is equal. It's a fast proxy for authority during prospecting. We use it at Ottawa SEO alongside Ahrefs Domain Rating and manual checks—no single metric tells the full story, but DA gives you a ballpark sense of whether a backlink will move the needle. It's also helpful for tracking competitor strength over time or justifying link budgets to clients who want a number to watch. Where DA misleads: it can be gamed with link spam, it doesn't account for niche relevance, and a DA 40 finance blog will outperform a DA 50 general directory for a mortgage broker. A site can have high DA but be penalized or irrelevant to your vertical. We've seen clients obsess over raising their own DA when they should focus on rankings and traffic—DA is a lagging indicator, not a target. Google cares about trust, relevance, and the actual link graph, none of which DA captures perfectly. Practical approach: use DA to filter prospects (we typically target DA 30+ for clients in competitive niches like legal or finance in Ottawa and Toronto), but always evaluate the actual page, its traffic, topical fit, and link profile before outreaching. Don't chase DA for DA's sake. A contextual link from a DA 35 industry blog beats a sitewide footer link from a DA 55 irrelevant site every time. Treat DA as one data point in a broader quality assessment, not as the scorecard for your link building campaign.