Question

What is the difference between a test cross , a back cross , a reciprocal cross and a dominant cross?

Answer 1

Test cross is a cross in which an individual with an unknown dominant phenotype is crossed with an individual (parent) homozygous recessive for that trait. It is used to check the homozygosity or heterozygosity of an individual.

Back cross is the cross that involves the mating of the F1 hybrid with one of its parent to achieve offspring with a genetic identity which is closer to that of the parent.

Reciprocal cross is a cross a pair of crosses to test the role of parental sex on inheritance pattern, it is done between a male of one strain and a female of another, and vice versa. 
Example: genotype A(female)   X    genotype B(male)    and    genotype B(female)   X    genotype A(male).

There is nothing called dominant cross, The character which appears in F1 generation is called dominant character. Eg- Tall height is dominant over short height

Answer 2

A test cross has a dominant phenotype and is used to establish an individual’s genotype. It is a cross to a homozygous  recessive genotype. It is used to determine the trait to be whether heterozygous or homozygous.

To determine if the trait is sex linked the reciprocal cross is done. It can be tested with both sexes of homozygous trait and crossing each of them with someone not having the trait and observe  the result.

Cross of F1 (F1 generation) to one of its parent is called the back cross. It is used for recovering elite genotype from any parent that possesses it.

There is nothing such as a a dominant cross, it's just a character present in the F1.  (F1) generation)