Two days after posting his résumé on a major job board, Jason Keith was called into his manager's office for a talk. His boss had found the résumé online and wanted to know if he was considering leaving. From there, he says, he was viewed as a lame duck.

Keith, 31, now a public-relations manager at VistaPrint in Lexington, Mass., left his position about six weeks later and admits he would handle his job search differently today.

With 47 percent of current employees searching for new jobs or planning to do so within the next year, according to Yahoo HotJobs, conducting a search in secrecy is important if job seekers don't want to jeopardize their current position or displease their higher-ups. A little discretion – and the features online job boards offer to allow people to remain anonymous – can help people avoid sabotaging a current position.

Job boards are catering to employed job seekers by allowing them to block certain companies from viewing their résumés. HotJobs's "hot block" and Monster's "privacy plus" allow seekers to prevent as many as 20 companies from looking at their résumés. However, the feature doesn't block recruiting firms the companies work with unless that recruiting firm's name is included on your block list.

Keith says he would have used this feature to block his former employer had he been aware of it.

Keeping parts of your résumé secret may also prevent your current employer or human-resources department from stumbling across your job search. TheLadders.com recently launched "bio confidentiality," which allows users to keep their name and current or previous employers anonymous. Since it was launched in March, more than 114,000 people have made some part of their résumés confidential.

Before the launch of bio confidentiality, Marc Cenedella, founder and chief executive officer of TheLadders.com, says it was the feature that was most requested by users.

Blind ads, in which the name of the company isn't specified, can also land job seekers in hot water. If the ad describes a position with responsibilities similar to yours, it's possible it could be from your current employer, says Brian Drum, president and CEO of Drum Associates, a New York-based executive-search firm.

He suggests applying only for positions that specify the company. Avoiding blind ads won't shut you out of too many positions: On TheLadders.com, 11 percent of ads are posted blindly and HotJobs estimates 5 percent of its ads are blind.

Attire can be a dead giveaway an employee is interviewing elsewhere. If your company is business casual and you show up at work in a suit on days you are interviewing, it can raise red flags. Instead, Beth Ross, a career consultant in Manhattan, suggests changing for interviews.

For interviews that may last longer than an hour, it may be wise to take a vacation or personal day, says Martin Yate, an executive-search strategist based in Savannah, Ga., and the author of "Knock 'Em Dead: The Ultimate Job Search Guide 2007."

Candidates also should be sure to separate their job from their search. "Under no circumstances should you use work e-mail or telephones to conduct your job search," Yate says. He suggests creating a private e-mail account for a search and using a cellphone or home number on a résumé.

Aside from increasing your chances of being exposed, using company resources to conduct a search could rub potential hiring managers the wrong way and give the impression that you're abusing company time.

"If they're sitting at their desk blitzing out their résumé, I would consider that disrespectful," said Lisa Tromba, vice president of Battalia Winston International, a New York-based executive-search firm. Tromba also dislikes it when candidates involve their administrative assistants in their job searches.

According to career coaches, a top rule of thumb is to conduct all correspondence from home. "The safest and most professional thing to do is to conduct your searching in the evening," Ross said. "You take a real chance when you do that at work."

Many companies routinely monitor their employees' Web surfing, and activity on career Web sites may spark suspicion. After auditing his server, Charley Polachi, co-founder of Polachi & Co., an executive-search firm in Boston, says he uncovered an employee's business plan to create a competing firm. He said the employee was fired after the incident.

Julia Zamorska, a 27-year-old account executive for Ruder Finn in Los Angeles, almost blew her cover when she was caught looking at a map of public-relations firms in Los Angeles while at her previous job. A colleague saw her computer screen and asked what was happening. Zamorska, who was working in San Francisco at the time, lied and said she was trying to get a better grasp of where her boyfriend lived in Los Angeles.

Using the company fax or printer to print or send résumés is equally unwise. Drum says he worked with a client who was terminated after a copy of his résumé printed out on his boss's printer.