A particular set of name servers fail DNS 0x20 only when queried over TCP, and typically also cause unbound’s capsforid fallback strategy to fail (not sure why, but it might be related to the different case returned in DNSSEC records by the particular servers). These servers are in the 194.0.1.0/24…

Widespread SERVFAIL problem related to DNS 0x20

mnordhoff January 23, 2019, 6:46pm 2

Incidentally, CommunityDNS also operates ns3.gratisdns.dk, which causes capsforid fallback failures by serving weird records with a weird class.

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