How did you learn about our vacancy?

This question is usually asked to understand through which channels candidates find the company and how effective your HR strategies are. You can honestly specify the source, for example:

• Professional job search sites (HeadHunter, LinkedIn, Indeed, etc.)
• Recommendations from acquaintances or colleagues
• Social networks and specialized communities
• Official company website or career section

Example answer: "I found out about your vacancy through LinkedIn, where you posted the job ad for an Android developer."