Once an interviewer asked me, "Can we use OSPF without area 0?" I was not able to answer at that time.
Later on, I searched, but I did not not find a satisfactory answer for this question. So, can we really use OSPF without Area 0?
There is only one way to use OSPF without an Area 0, and that is to use OSPF with a single area. If you only have one OSPF area, you can number it any way you like, but if you have even two areas, you must have an Area 0.
If not using area 0 or backbone area then it means that single area ospf is being implemented here..
What is single area ospf read it here:- http://learnwow.blogspot.in/2017/10/ospf-in-networking-top-standout-characteristics.html
No OSPF should have a backbone area because it acts as a hub to transmit routing information about other areas in the network.