"If you could ask a job candidate only one question, and had to make a hiring decision solely on the basis of the answer, what would the question be?" CNBC contributor Adam Bryant asked LinkedIn CEO Jeff Weiner this question during a fascinating interview. Weiner's unhesitating answer: "What's your ultimate dream job?"

He explains, "It's not just changing the world--that's not entirely helpful in that context. It's literally, if you could write down your perfect job, the company, the role, you name it, your job description--what does that look like?" The response to that simple question tells him a lot of what he needs to know, he says.

Why is that one question so valuable? "It helps me get a sense of who you are by virtue of the specificity of that answer," Weiner explains. With young job candidates, he doesn't expect a lot of specifics, knowing that people at that time in their lives are still trying to find the right direction for their careers. "But the longer you've been in the workforce, I think it's really helpful to know what it is you ultimately want, because I think once you know what it is you ultimately want, you are that much more capable of manifesting it." 

The second reason he loves that question is that it helps him see whether the candidate and the job will be a good fit for each other over the long term. "Oftentimes, both the candidate and the company or the hiring manager over time become increasingly fixated with closing the deal--with getting the offer or getting the candidate to accept the offer," he explains. The problem is that making a hire isn't the end of the process, it's just the beginning of what you hope is a long relationship. "It's like a couple getting together and putting all their energy into their wedding day without thinking about what's going to make for a successful, long-lasting marriage." That's why understanding how a candidate would fit with the role he or she is interviewing for is really valuable, he says.

Do people ever respond that the job they're actually interviewing for is their dream job? Fortunately, Weiner says, only a very few people have ever said that. "I think people recognize the importance of authenticity," he adds. 

"I want your job"

What about candidates who say their ideal job is Weiner's job--CEO of LinkedIn? That, too, has only happened a very few times, he reports. But he'd be fine if it happened more often. "I love that response," he says. "Somebody who has that sense of what they want to do longer term, that's the kind of person you want to take the time to coach and potentially mentor." That's especially true if the person has the aptitude and capabilities to someday fulfill a CEO role, whether at LinkedIn or another company or as a startup founder, he adds.

But it has to be for the right reasons. Weiner says he's less interested in candidates who aspire to a CEO role because of the title or salary or perks, or the power that comes with it. "To the extent they've looked forward to the day when they can help steer a company, when they can help codify and put a stake in the ground on vision, on mission, on culture and values and strategy, and help bring people along and build incredible teams, and deliver products that help change the lives of the people those products ultimately serve--it's exciting to hear an answer like that," he says. 

It's a mark of Weiner's maturity, and wisdom as a leader, that he finds that answer exciting as opposed to threatening. What would you say if a job candidate told you that your job was that person's dream job?