Inded. The old RFCs are just the tip of the iceberg, and in the end you have to pretty much ask "What would BIND do?".
Zone master files are a great example of this. There's no official grammar and so there are subtle differences in the way different DNS servers parse them.
Its also easy to under-estimate and not notice for example, until you've written a lexer or two, that the grammar is context sensitive and ambiguous... so I'd almost guarantee that trust-dns can be made to interpret one differently to BIND, Knot, or unbound.
Zone master files are a great example of this. There's no official grammar and so there are subtle differences in the way different DNS servers parse them.
Its also easy to under-estimate and not notice for example, until you've written a lexer or two, that the grammar is context sensitive and ambiguous... so I'd almost guarantee that trust-dns can be made to interpret one differently to BIND, Knot, or unbound.