Answer:
1. Verbal Irony
Although Danforth says that "I judge nothing", his literal role in the play is that of a judge.
2. Situational Irony
Considering that Elizabeth Proctor is an honest woman, no one would expect her to lie, especially in court under oath.
3. Dramatic Irony
Proctor means that God is no longer in charge of Salem, the devil is and he is able to do his work through those that lie and falsely accuse other, as well as the corrupt court which takes innocent victims.
4. Dramatic Irony
We have all of the evidence that the girls are lying about witchcraft but the court and Danforth are still naive to their lies.
Miller included so much irony to create tension in important scenes. It is to develop tension for the audience and create more drama within the story to make it more interesting.