abstract fun lookup4(name: String, handler: Handler<AsyncResult<String>>): DnsClient
Try to lookup the A (ipv4) record for the given name. The first found will be used.
handler - the Handler to notify with the io.vertx.core.AsyncResult. The handler will get notified with the resolved java.net.Inet4Address if a record was found. If non was found it will get notifed with null. If an error accours it will get failed.
Return
a reference to this, so the API can be used fluently