Do you want to ask Ali and Youku? According to official website's query, Boss Direct Employment, Ali Company and Youku Company will certify the information provided by the interviewer in the last round of interview, mainly to ensure the authenticity of the interviewer's information. Back tone refers to background investigation, also known as "verification proof materials". Consulting the former boss, colleagues, academic institutions and referees of candidates is an effective way to verify the background materials of candidates and prove the authenticity and effectiveness of the materials.