These are one time-use passcodes generated by the Duo Mobile application. You can use this code as your two-step login with Duo on all services.
These are sent to your device via an SMS text message. When requested, you will receive one code in a text message. SMS codes are single-use and if you send multiple codes to your phone, only the most recent code is valid.
These are generated from the Duo Administration Service. Rutgers OIT Help Desk can provide these codes based on user needs. Each bypass code is good for 2 uses for two hours after the code is generated. You can use these codes to authenticate with your two-step login with Duo on all services. In order to avoid needing a bypass code, it is encouraged to have a second device on one's Duo account.