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firewall dns tcp
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.
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...
1221
adv200013
dnsdns cache
dns forwarders
dns over tcpdns registry
dns security
edns0
firewalldnstcp
maximumudppacketsize
powershell
registry hardening
security tips
server core
tcpdns latency
windows server
windows server 2022
windows server 2025