Specific kinase that phosphorylates deoxyadenosine but not any other deoxyribonucleoside, as part of the deoxyribonucleotide salvage pathway. 2'-deoxyadenosine + ATP = ADP + dAMP + H(+) Catalytic efficiency is 100-fold higher for deoxyadenosine than for thymidine. Can also efficiently phosphorylate medically important adenosine analogs, such as 9-beta-d-arabinofuranosyl-2-fluoroadenine (fludarabine). Belongs to the DCK/DGK family.