Final answer:
Information Warfare Officers (designator 1640) must be commissioned before their 42nd birthday, but waivers may be available in exceptional cases.
Step-by-step explanation:
To become an Information Warfare Officer (designator 1640) in the United States Navy, candidates must be commissioned before their 42nd birthday. This allows officers sufficient time to complete the necessary training and meet the service requirements for their military career path.
However, it's important to note that there may be waivers available for exceptional cases. It is always best to check the most current instructions from the U.S. Navy or consult with a Navy recruiter for the most up-to-date information and any potential changes to commissioning age limits.