I understand that SCJP is mandatory for writing SCWCD. But when I booked the slot or wrote the exam yesterday, no body asked me If I was SCJP certified. How does SUN find that out if some one has cleard the pre-requiste or not ??
sun stores your id and cleared certificates in a database. You can entry the certmanager (http://www.certmanager.net/sun) and have a look. without being scjp first you should not be able to book the scwcd exam.