# Match replies to outstanding DNS queries before accepting an answer > Use RFC 5452 — Measures for Making DNS More Resilient against Forged Answers to review this narrow operational decision without extending the source beyond its stated scope. - Canonical URL: https://update.dsesecurity.com/updates/match-replies-to-outstanding-dns-queries-before-accepting-an-answer/ - Publisher: Detection Systems & Engineering (DSE Security) - Author: DSE Security Editorial Team - Published: 2026-08-27T12:17:38+00:00 - Modified: 2026-08-27T12:18:09+00:00 - Last reviewed by DSE: 2026-08-26 - Resource type: Explainer - DSE priority: Advisory - Topics: Cybersecurity, Networks & Infrastructure - Reading time: 3 minutes ## What you need to know Use RFC 5452 — Measures for Making DNS More Resilient against Forged Answers to review this narrow operational decision without extending the source beyond its stated scope. ## Potentially affected Teams, systems, services, or facilities within the stated scope of RFC 5452 — Measures for Making DNS More Resilient against Forged Answers ## DSE recommendation Compare the observed state with the cited official source, document applicability and exceptions, and test any approved change with rollback safeguards. ## Article Frame this document as a source-led configuration and assurance check: Match replies to outstanding DNS queries before accepting an answer. Only the official source and traced locations below supply facts. Confirm applicability before acting. ## Source fact: The official [RFC 5452 — Measures for Making DNS More Resilient against Forged Answers](https://www.rfc-editor.org/rfc/rfc5452.html) from RFC Editor / Internet Engineering Task Force supports the following bounded statements: - Before accepting a DNS reply, a resolver must match its addresses, destination port, query ID, query name, query class, and query type to the outstanding query. The research record locates this support at Section 9.1 (Query Matching Rules). - Resolvers must choose outgoing query IDs unpredictably across the full 16-bit range and use the largest practical unpredictable source-port range. The research record locates this support at Section 9.2 (Extending the Q-ID Space by Using Ports and Addresses). - With multiple outstanding queries, a resolver must use multiple source ports; a resolver with multiple addresses should also vary its outgoing address unpredictably. The research record locates this support at Section 9.2 (Extending the Q-ID Space by Using Ports and Addresses), concurrent queries. These statements are the factual basis for this document. Do not extend them into a broader assurance. Review authoritative zones, delegations, resolvers, caches, record owners, and the clients that consume the resulting answers only where the source and recorded environment align. ## What the source does not establish This RFC evidence supports only the named DNS protocol decision; it does not prove Windows implementation support or a safe production configuration. No current deployment state or change approval follows from the source alone. Validate Windows DNS roles, Active Directory-integrated data, forwarding paths, time, routing, firewalls, and registrar or registry state, and treat examples or options as conditional inputs rather than defaults. ## Applicability questions - For source statement 1 at Section 9.1 (Query Matching Rules), which observable configuration, record, or test can confirm applicability here? - For source statement 2 at Section 9.2 (Extending the Q-ID Space by Using Ports and Addresses), which observable configuration, record, or test can confirm applicability here? - For source statement 3 at Section 9.2 (Extending the Q-ID Space by Using Ports and Addresses), concurrent queries, which observable configuration, record, or test can confirm applicability here? - Within authoritative zones, delegations, resolvers, caches, record owners, and the clients that consume the resulting answers, which versions, roles, and configuration states define the review population? - Could Windows DNS roles, Active Directory-integrated data, forwarding paths, time, routing, firewalls, and registrar or registry state invalidate the test, hide a failure, or change applicability? - Who owns the decision, and which observation requires stopping, escalation, or rollback? ## DSE recommendation: DSE recommends using the cited source as the evidence anchor for this decision. Start with applicability, then compare the observed state with the cited source. Record the source location, examined part of authoritative zones, delegations, resolvers, caches, record owners, and the clients that consume the resulting answers, observed and expected states, owner, and reason for deviation. An implementation decision needs an owner, approved window, prechecks, observable outcome, stop authority, and rollback path. Validate Windows DNS roles, Active Directory-integrated data, forwarding paths, time, routing, firewalls, and registrar or registry state before and after the test, and store only sanitized operational evidence. ## Verification and evidence Evidence should let another reviewer reproduce this decision. Retain observations beside the traced locations Section 9.1 (Query Matching Rules); Section 9.2 (Extending the Q-ID Space by Using Ports and Addresses); Section 9.2 (Extending the Q-ID Space by Using Ports and Addresses), concurrent queries. Favor zone data, packet captures, query transcripts, delegation checks, resolver configuration, and negative-answer behavior, linked to stable identifiers, time, and operator. Close the review only when the evidence, exception handling, resulting action, and after-state are linked. Schedule a new review after material technical, organizational, incident, or source changes; today’s observation is not a continuing guarantee. ## Official references - [RFC 5452 — Measures for Making DNS More Resilient against Forged Answers](https://www.rfc-editor.org/rfc/rfc5452.html) — RFC Editor / Internet Engineering Task Force ## Primary reference - Name: RFC 5452 — Measures for Making DNS More Resilient against Forged Answers - Authority: www.rfc-editor.org - URL: https://www.rfc-editor.org/rfc/rfc5452.html - Source publication date: Not stated by the source ## Citation and use Preferred citation: “Match replies to outstanding DNS queries before accepting an answer,” DSE Security, https://update.dsesecurity.com/updates/match-replies-to-outstanding-dns-queries-before-accepting-an-answer/ Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/ Usage and citation policy: https://update.dsesecurity.com/usage/ Copyright © 2026 Detection Systems & Engineering. 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