Before answering this, it helps to be clear about what domain authority actually is. Domain Authority, often shortened to DA, is a score created by the SEO software company Moz. It runs on a scale of 1 to 100 and is meant to predict how well a website might rank in search results. It is a third-party estimate. Google does not use Domain Authority, and Google representatives have stated plainly that it is not a ranking factor. So an SEO company cannot improve your DA score directly, and any provider promising a specific number is making a promise it cannot keep.
What an SEO company can do is improve the real underlying authority that a score like DA tries to reflect. Moz calculates DA largely from the quality and quantity of links pointing to a site. When the genuine signals improve, the score tends to follow. The work is about strengthening the site itself, not chasing the number.
Earning quality, relevant backlinks
Links from other websites are still one of the strongest signals of trust. An SEO company works to earn links from sites that are credible and, just as important, relevant to your subject. A link from a respected source in your own industry carries far more value than a link from an unrelated site, even if that unrelated site has a high score of its own. A link to a financial services site from a gardening blog does very little.
Reputable providers earn these links rather than buy them. Buying links violates Google’s spam policies and can lead to penalties. Earning links instead means activities such as digital outreach, contributing useful expert commentary, getting the business cited in industry publications, and correcting or reclaiming mentions that do not yet link back. The goal is a steady flow of links that a site genuinely deserves.
Building topical authority through content
Authority is not only about links. It is also about depth. Topical authority means becoming a thorough, trustworthy source on a specific subject. An SEO company builds this by planning content as a connected system rather than a pile of unrelated articles.
In practice, this means covering a core topic with a main page and then supporting it with detailed articles on the related subtopics. These pages are linked together so both readers and search engines can see that the site treats the subject completely. Over time, this signals real expertise. It also tends to attract links naturally, because thorough, accurate content is the kind of thing other people choose to reference.
Creating content worth linking to
The most sustainable way to earn links is to publish material that others want to cite. This can include original research, useful data, clear guides, or tools that solve a real problem. An SEO company helps identify what your audience and your industry actually need, then produces content strong enough to be referenced on its own merit. This reduces the need for constant outreach, because the content does some of the work itself.
Maintaining a healthy link profile
Authority can be undermined by a poor link profile. An SEO company reviews the links a site has already accumulated and watches for patterns that look manipulative, such as large numbers of low-quality or spammy links. Where needed, it cleans up or disavows links that could be harmful. It also fixes broken links and resolves technical issues that waste the value of links the site has earned. The aim is a link profile that is natural, relevant, and free of obvious red flags.
What to expect
Improving genuine authority is gradual work. It usually takes many months of consistent effort before the results are clear in either rankings or in a third-party score. A trustworthy SEO company focuses on the actual drivers of authority, quality links, deep content, and a clean link profile, and treats any movement in a Moz score as a side effect of that work rather than the goal itself.