As of 16 April 2018, you have to make an appointment online for a DNA test.
When does the IND offers you a DNA test?
The IND can offer you a test if you applied for a 'making a journey in connection with family reunification with an asylum seeker'.
Family members who want to come to the Netherlands then have to prove their identity and their (family) relationship with you in the Netherlands. This can be done by means of (official) documents, such as a passport or birth certificate. If these documents are not sufficient or missing through no fault of your own, the IND can offer you a DNA test. You will then receive a DNA letter from the IND.
When you have received a DNA letter, you can make an appointment online at the IND desk in Utrecht.