Few companies go far on Employment verification as per their policy. Rules and regulations framed by companies change from country to country. The depth of a background check will give more insights into a candidate to companies for taking a decision in the hiring process.
For example, they go in-depth in academic, professional qualifications and criminal background checks. companies either directly do a background check or they hire best background screening companies like IDA.
As per norms check to go back to 7 years. A candidate will come to know the status of a background check when he contacted his previous employer directly or indirectly.