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They're not valid DNS names, they're IP addresses. When you subscribe to an Internet Service Provider you are actually subscribing to the network using the IP address space. DNS is an add-on that is overlayed on top of the IP addressed network. If anything, allowing host resolvers besides DNS should be a more transparent process, like switching out your default search engine.

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IPv4 addresses can be parsed as host names per RFC 1123 section 2.1; it is merely convention ("SHOULD") that dotted numbers are checked as IP addresses before being passed through DNS.

This is what the parent meant. IPv4 addresses are also syntactically valid host names.

> IPv4 addresses are also syntactically valid host names.

Curious...from the philosophical intent supporting the normative language[1] (my emphasis added):

However, a valid host name can never have the dotted-decimal form #.#.#.#, since at least the highest-level component label will be alphabetic.

[1] https://tools.ietf.org/html/rfc1123#page-13

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