Replaces recursive queries to root servers (which don't answer RD=1)
with proper iterative resolution through the delegation chain.
Reduces per-query timeout from 5s to 700ms.
Fixes the root cause of make check hanging: resolveARecord and
resolveNSRecursive were sending recursive queries to root nameservers,
which silently dropped them, causing 5s timeouts × retries × servers.
closes#24
