Must every magnetic field configuration have a north and a south pole?What about the field due to a toroid?

It is not necessary that every magnetic field configuration have a north and a south pole.
This is true only if thr source of field has a net non-zero magnetic moment.

This is not so for a toroid or even for a straight infinite conducter

Magnetic Field of Toroid is shown in below figure...

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Naga Ramesh
IIT Kgp - 2005 batch