Potential on a surface of a sphere produced by a dipole source inside

Dear all,

I would like to calculate electrostatic potential distribution on a surface of a homogeneous conductive sphere produced by a dipole source inside of this sphere. I have created a sphere and a dipole point source at the centre. I would like to ask the following question: do I need to create another outer sphere (enclosing the original sphere) in order to calculate the potential distribution correctly? According to the examples I see in the discussion forum many people use the outer sphere. What is the purpose of the outer sphere? Is it necessary to enforce the zero charge condition (n*D = 0)? Thank you.

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Kind regards,
Maksims