Function resolve

lib/internal/dns/promises.js:350–365

(hostname, rrtype)

}

function resolve(hostname, rrtype) {
  let resolver;

  if (rrtype !== undefined) {
    validateString(rrtype, 'rrtype');

    resolver = resolveMap[rrtype];

    if (typeof resolver !== 'function')
      throw new ERR_INVALID_ARG_VALUE('rrtype', rrtype);
  } else {
    resolver = resolveMap.A;
  }

  return FunctionPrototypeCall(resolver, this, hostname);
}

// Promise-based resolver.
const { Resolver, resolveMap } = createResolverClass(resolver);