// Package traverse implements the core DNS traversal engine for ExploreDNS,
// a Go port of the Ruby dnstraverse engine (dns.squish.net).
//
// The traversal starts from a synthetic "rootroot" node (never displayed)
// with one child per root server, and explores every branch of the
// delegation instead of stopping at the first authoritative answer, so lame
// delegations, missing glue and split authorities are all visible.
//
// # Architecture
//
// A Traverser runs an explicit stack loop over Referral nodes. Each Referral
// queries every IP address of one nameserver for one qname/qclass/qtype,
// classifies each response (DecodedQuery, ServerResponse) and creates one
// child per NS name for referral/restart statuses — including glueless
// nameservers, which get their own resolve subtree (refid ".0." components)
// queried from this branch's cache, never a system resolver. Post-order
// stack markers fold the statistics upwards once all children finished:
// every leaf outcome carries a probability, and the probabilities at the
// root sum to 1.0.
//
// # Caching
//
// Two caches cooperate: the packet-level cache in internal/dns sends each
// (server IP, question, udpsize) at most once per run, and the hierarchical
// per-branch InfoCache holds the in-bailiwick records each response is
// allowed to contribute. Fast mode (default) additionally memoises completed
// referrals so identical subtrees are reported as "completed earlier"
// instead of being walked again.
package traverse