restrictive covenant in restraint of trade in service agreement

Convenant in restraint of trade-Contract Act, 1872, Section 27, scope of-Whether a post-service restrictive covenant in restraint of trade in service agreement between the parties is void-Even if it be valid, whether it could be enforceable, as enjoined by illustrations (c) and (d) to Section 57 of the Specific Relief Act, 1963.