Selective service registration
In general, all males between the ages of 18 and 26 years of age are required to register for the Selective Service. This applies to every male individual regardless of your immigration status.
At the moment of filing your application for Naturalization it is a requirement to provide evidence of your Selective Service registration.
If there is no registration found then you will need to provide a Notarized Affidavit explaining why you did not register during that period.
To Verify your Registration: https://www.sss.gov/verify/proof/