顶级域中的数字?
顶级域的末尾可以包含数字吗?我对 DNS 规则等一无所知，但是当我尝试将 PHP 的 filter_var() 函数与 FILTER_VALIDATE_EMAIL 一起用于 test@null.com1 时，它返回 true.
Can top-level domains contain a number at the end? Idk nothing about DNS rules etc but when I try to use PHP's filter_var() function with FILTER_VALIDATE_EMAIL for test@null.com1 it returns true.
推荐答案
从概念上讲，TLD 中没有禁止数字的内容 未来，谁知道呢，也许会出现数字顶级域名.
Conceptually, there is nothing that disallows numbers in a TLD and in the future, who knows, perhaps there will be numeric TLDs.
目前没有包含数字的 TLD - 该函数可能不会针对已知 TLD 列表进行测试(因为它可能会发生变化)，而是在词法上进行测试.
There are no TLDs at the moment that do have numbers in them - the function probably does not test against a list of known TLDs (as it is subject to change), but lexically.
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