It depends on where in Ranui. It could be 0612 or 0614 go to http://www.nzpost.co.nz/Cultures/en-NZ/OnlineTools/PostCodeFinder/ to enter the exact address.
Manurewa. Manukau City in Auckland Region.
The National Bank of NZ
The code is AKL.
post code for New Lynn is 0600
3434
1008
12233
2022 Auckland / Manukau City / Mangere Bridge.
Manurewa. Manukau City in Auckland Region.
The postal code of Glen Eden Auckland is 0602 =)
The National Bank of NZ
1072
The code is AKL.
post code of Three Kings
632005
6100
You can find it at nzpost.co.nz