Datadog Softeware Engineer interview questions

I was contacted by a recruiter and then there was the first step about technical knowledge and coding. I passed this one and then there was a n home assignment, an application to analyze logs and to raise alerts according to some rules. The funny thing is that the log was not provided, so I also needed to build something to generate the log. Unfortunately my test was rejected even if the outcome was a bit controversial. The engineer reviewing the test didn´t know java so he found the application complex and difficult to understand, without enough documentation but I spent a lot of time for testing, providing a ui and also providing something to generates the logs that were not provided. I had a bad feeling honestely, it was not clear to me where to invest time. I spent a lot of time for something that was not considered enough in my opinion. Also the fact that the reviewer didn´t know java didn´t help in my opinion. I was disappointed a bit by the result and also the recruiter had a lot of doubts