Is down's syndrome a recessive condition?

No. Down syndrome is not a recessive condition. It is caused by an extra chromosome #21. We normally have a pair (=two copies) of each chromosomes #1-22. Individuals with down syndrome have a third chromosome #21. Thus name "trisomy 21" as well. Here more about mechanism and heritability of down syndrome if you are interested: http://ghr.Nlm.Nih.Gov/condition/down-syndrome.