One of the most frequent questions that employers ask candidates during a job interview is if they can contact your current/most recent employer. This is especially tricky if you are still employed. After all, most people don't want their current employer finding out that they are job hunting. Here is how to answer this tricky job interview question.
If you encounter this question on the employment application, simply check the "Yes" box, and then write the following sentence "May contact employer after offer is given." This way you will have a job offer before your employer finds out you are job hunting.
If the company no longer exists, then simply tell them this. In today's job market this is not unusual at all and will not be held against you. However, know that the new employer will usually verify bankruptcies and company closures, so don't try to lie to avoid having them check out your previous company.
If you were fired, then tell them no. Even if you left on good terms with your past employer, you don't want the human resources department to call and get their side of the story before you get completely through the interview process.