The 561st Network Operations Squadron (NOS) has a requirement for 70 subscription-based services that provide live virtual instructor-led classrooms for Cyber training and includes exam vouchers as ou... The 561st Network Operations Squadron (NOS) has a requirement for 70 subscription-based services that provide live virtual instructor-led classrooms for Cyber training and includes exam vouchers as outlined below. An exam voucher is defined as a prepaid authorization code or certificate that allows an individual to register for and take a specific certification exam without paying for the exam fee directly at the time of registration.