Fig. 1.

DNS tree for querying A example.com., including all zones (round) and NSs (square) that may be involved in a resolution (Fig. (a)). The minimal set of queries, five, for the best case is shown in Fig. (b). It assumes that glue for resolving example.com can be trusted. The corresponding zones and authoritative servers of Fig. 1a are highlighted in red. ZDNS would explore a sub-tree close to this subset, while our system explores all possible paths (gray). (Color figure online)