We report on magneto-optical resonances observed in sodium fluorescence from D2 manifold with an intensity-modulated light. Fluorescence resonances are measured in the perpendicular (90°) and backward (180°) directions to the light propagation in laboratory experiments using a sodium cell containing neon buffer gas. Properties of these resonances are studied by varying the magnetic field at fixed-light modulation frequency, and vice-versa. Modulation with low-duty cycle shows higher-harmonic resonances of the modulation frequency and sub-harmonic resonances of the Larmor frequency. A dark resonance with maximum amplitude for laser wavelength closer to the crossover peak is observed. The origin of this dark resonance observed in Na D2 line is discussed using a theoretical model. Present study is aimed towards improving the understanding of magneto-optical resonances for remote magnetometry applications with mesospheric sodium.