Just for informaton of all, Some job applications come with ZIP code requests. In that regard Nigeria does not use ZIP code as it's a function of American postal system of which Nigerian international ZIP code is 00176-0000, but if you leave it blank, no one will penalize you. Coming to Postal codes as used in Nigeria,
Not all areas in Nigeria have Postal code because if you check the data base of Nipost, a place like karu, Abaji, gwagwalada etc has no recorded postal code, because the streets are not documented thus this makes a rubbish of the postal code requested in some job sites.