Cisco certification is a certification system, which contains a variety of certifications, different certifications and their re-certification methods are not the same, the more common are the following three: CCNA re-certification: you can re-take the ccna exam, you can also directly test one of the ccnp exams, exams passed in order to continue to use the ccna. ccnp re-certification: there are three ways to refresh the validity of the exam, test a ccnp core Exam, or examined two ccnp elective exams, or examined CCIE experimental exams. ccie re-certification: ccie is valid for three years, the validity of the expiration date, you must retake the written and experimental exams, exams over to refresh the validity of the ccie certificate.