[1] RFC 2606 - Reserved Top Level DNS Names, 3/28/2021, 7:19:55 AM, 4/9/2021, 8:41:39 AM https://tools.ietf.org/html/rfc2606#section-2
[2] RFC 6761 - Special-Use Domain Names ( (6/27/2013, 1:35:13 PM 版)) http://tools.ietf.org/html/rfc6761#section-6.5
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