Final answer:
Without specific context, it is challenging to determine the exact recertification period for CDU training as requirements vary by profession and certifying organizations. It is important to refer to the guidelines of the specific CDU program in question, as many similar certification programs typically require recertification every 2 to 3 years.
Step-by-step explanation:
The term CDU often refers to Continuing Development Units, which are part of professional development programs in various industries to maintain certification. However, without specific context, it's challenging to determine exactly which CDU program this question refers to as requirements can differ between professions and certifying organizations. Generally, many certification programs require professionals to recertify or complete continuing education within a certain time frame to ensure their knowledge and skills remain current. For many certifications, recertification is required every 2 to 3 years. However, it's crucial to check the specific requirements of the certifying body of the CDU program in question. If this is related to a niche or industry-specific CDU, the requirements could be unique.