Help resolving a DNS configuration error during lookup. How is DNS resolution implemented?

[paul-palmer]

I get the following error when trying to make a request:

Mar 02 21:39:02 hooker.dev.bpp webhook-server[3719]: res: Err(FailedRequest(hyper_util::client::legacy::Error(Connect, ConnectError("dns error", Resolve(ResolveError { kind: Proto(ProtoError { kind: Io(Custom { kind: Other, error: "Error parsing resolv.conf: option at line 4 is not recognized" }) }) })))))

How does hyper perform DNS lookups? Is this builtin or does it delegate to another crate? I need help tracking down where this error originates so that I can request a fix (as the line in question in /etc/resolv.conf is a correct one).

[seanmonstar]

Whoever created the client will have need to provide a DNS Resolver implementation. Two popular ones are GaiResolver, which just delegates to getaddrinfo, and another is hickory-dns, which might be trying to parse it and not understanding some options. Or it could be something else entirely, since hyper allows any implementation.

[paul-palmer]

Thank you.