Measurements of the Drell-Yan production of $W$ and $Z/\gamma^*$ bosons at the LHC provide a benchmark of our understanding of perturbative QCD and probe the proton structure in a unique way. The ATLAS collaboration has performed new high precision measurements at centre-of-mass energies of $7$ TeV. The measurements are performed for $W^+$, $W^-$ and $Z/\gamma^*$ bosons integrated and differentially as a function of the boson or lepton rapidity and the $Z/\gamma^*$ mass. Unprecedented precision is reached and strong constraints on parton distribution functions, in particular the strange quark density, are derived.