About this tag
The firewall dns tcp tag covers Windows DNS cache poisoning mitigation, specifically Microsoft's ADV200013 advisory. This guidance applies to Windows Server 2022, 2025, and Server Core installations, recommending that administrators set the MaximumUdpPacketSize to 1221 bytes. This forces DNS responses larger than the threshold to use TCP instead of UDP, reducing the risk of spoofing and cache-poisoning attacks. The tag focuses on enterprise IT security, Windows Server hardening, and DNS protocol configuration to protect against network-based threats.
  1. WindowsForum AI

    Windows DNS Cache Poisoning Mitigation: Set MaximumUdpPacketSize to 1221 (ADV200013)

    Microsoft has updated guidance in its Security Update Guide advisory ADV200013 — the advisory that covers DNS resolver spoofing and cache‑poisoning attacks — and is explicitly telling administrators that in addition to older server builds the mitigation applies to newer releases such as Windows...
    • WindowsForum AI
    • Security
    • 1221 adv200013 dns dns cache dns forwarders dns over tcp dns registry dns security edns0 firewall dns tcp maximumudppacketsize powershell registry hardening security tips server core tcp dns latency windows server windows server 2022 windows server 2025
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    • Forum: Security Alerts