I gather that what you want is a fairly symmetrical pattern, more dense in the middle than at the edges, probably centered a bit above the point of aim.
我想你要得到的是一个很对称的模式。中部的密度比周围大,可能集中在目标之上的某一点。
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An IP address matches a netmask based on precise bitpattern matching rules (beyond the scope of this article).