Bulk Reverse DNS

PTR records are what a mail server sees when you connect to it, and the first thing it judges you on. This resolves a whole range at once so you can spot the addresses that answer with nothing, or with the hosting provider's default name.

Range or addresses: An IPv4 CIDR block, or addresses (v4 or v6) one per line. At most 64 per run — each one is a separate query to a public resolver.

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