  A measurement of the electroweak production cross section of a Z boson and
two jets is performed using proton-proton collision data at centre-of-mass
energies of 7 and 8 TeV. The data is collected by the CMS experiment at the LHC
with an integrated luminosity of 5 and 19 fb$^{-1}$, respectively. A study on
the hadronic activity between the two tagging jets is also presented.
