Dear Matt: I was offered a job but it was withdrawn because my references didn’t check out. I talked to the three I gave and none of them had heard from the employer. What’s going on?

Matt says: The days of providing three references and expecting them to be the only sources employers check with are long gone, says Chris Dardis, VP of HR Search and Consulting for Versique (versique.com), a Minneapolis-based executive search firm. Many employers may not check the references you give them and it’s perfectly legal, because a prospective employer does not require your permission to check any references. Employers are also relying on new tools and tactics to research potential candidates’ backgrounds.

“Social media sites such as LinkedIn, Facebook and Twitter are the first place hiring managers tend to explore candidate information,” says Dardis. “Whether you think it’s right or wrong, potential candidates need to be aware of the brand they are displaying on the Internet.”

If you are using online job sites to float your résumé, be aware that employers also search those and can see if your online résumé matches the information provided to them, says Jeff Shane, spokesperson for Allison & Taylor Inc. (allisontaylor.com), an employment verification and reference checking firm. They may also pull references from these sites and contact those people, even if they’re not names you provided on your application. “Don’t assume that employers will only check with human resources or your former supervisor for reference purposes,” says Shane. “Employers are increasingly scrutinizing less-traditional references such as peers and co-workers.”

Employers also use tools like Checkster (checkster.com), which provides quantifiable data on the candidate. Employers also use their own network and conduct what is known as “backdoor reference checks” to learn about the candidate’s previous employers, identify where they have connections and call around to simply inquire about their reputation — all without the candidate’s knowledge.

“These days, it doesn’t necessarily matter what your official references are saying,” says Dardis. “What matters is the kind of reputation you are leaving in the marketplace.”

Don’t ignore the value of your reference list, but go beyond just names and contact information. An effective reference provides the attributes they can attest to on your behalf, says Shane, allowing you to showcase your abilities and achievements and tie those qualifications to the key elements sought by new employers. Allison & Taylor provides numerous sample reference formats on its website.

“When offered to a potential employer at the close of an interview, a well-crafted reference document will make a powerful and proactive statement on the job seeker’s behalf,” says Shane.

Contact Matt at jobslink@startribune.com.