We report on the synthesis of spinel Co1-xZnxFe2O4 (x=0.00.56) ferrites by sol-gel auto-combustion method. Xray diffraction 'XRD', magnetic measurements were used to study compositionaldependence of structural, magnetic properties, connection among them. Mössbauer spectroscopy was used to identify non-magnetic-phase, its effect on magnetic properties. Single-phased nano spinel-ferrite formation is confirmed by XRD. Increasing Zn-content leads to structural modifications such as decrease of lattice parameter, grain diameter DW-H, alteration of inversion parameter, disorder, tensile-strain, dislocation density, variation of A-O-B, A-O-A, B-O-B superexchange-interaction and canting angles. Cationic distribution suggests that Fe 3+ , Co 2+ ions reside on both A, Bsites, and with increasing Zn-content, B-site population of Fe 3+ , Zn 2+ ions increases; while that of Co 2+ ions decreases. Saturation magnetization shows noticeable dependence on canting angle suggests that the magnetization in the studied samples is described by Yafet-Kittel three-sub-lattice model. Coercivity Hc values are consistent with anisotropy, and its dependence on DW-H suggests that the studied samples are in overlap-region between multiple-domains/single-domain. Reduced-remanence indicate the variation of inter-grain magnetostatic-interaction, isotropic-behavior of multi-domain particles. Observed broad peaks in magnetization derivative with field suggest large-number of dislocations, more-uniform particle-size. Switching-fielddistribution proposes potential application of the studied x=0.0 sample in high density recording, and sample with x=0.56 in targeted drug delivery. Mössbauer measurements confirm three-magnetic-components corresponding to A,B-sites, Fe3+ ions in grain boundaries/surface, Fe has 3+ oxidation state, and growing paramagneticdoublet, alone does not explain the trend of Ms, suggesting that it is a collective-effect of structural-modification, presence of paramagnetic-doublet.