Domain Authority remains relevant as a third-party estimation tool, not because Google uses it (they don't), but because it approximates the link equity and trust signals Google does evaluate. When you're comparing two potential link sources or deciding whether a domain in your portfolio deserves more investment, DA gives you a quick directional read. A DA 65 site will generally outrank a DA 25 site if all else is equal, because DA correlates with the underlying factors Google cares about: diverse backlink profiles, referring domain counts, and historical trust. The metric breaks down in specific scenarios. Brand-new sites with zero DA can rank immediately for low-competition keywords. Niche authority sites with DA 30 often outperform DA 50 generalists in their vertical. PBNs and link farms can inflate DA through manipulative link schemes while having zero real ranking power. DA also updates slowly, so a site that just earned 50 quality links won't reflect that for weeks. At Ottawa SEO, we use DA as one input among several when evaluating link opportunities or portfolio acquisitions. We'll pass on a DA 40 site if the backlink profile is spammy, and we'll pursue a DA 18 site if it has clean links and topical relevance to our client's niche. For our 500+ domain portfolio, DA helps us triage which properties to prioritize for content updates or which to consider selling. Better approach: combine DA with manual backlink audits (check for spam ratios, anchor diversity, referring domain quality), traffic trends in Ahrefs or SEMrush, and topical alignment. If you're purely link prospecting, DA above 30 with clean link profiles is a reasonable baseline for outreach targets. If you're buying domains, don't pay a premium solely based on DA—verify the links are real, the traffic existed, and Google hasn't penalized it. DA is a shortcut, not a strategy.