Docker Windows containers have a number of shortcomings, particularly around networking. One showstopper is that it doesn’t use the DNS of its host server. The expected behaviour in (Linux) Docker containers is that the Docker engine creates a virtual DNS for containers. The Docker DNS resolves containers by name (for Docker Swarm / Docker Compose) or delegates to the host DNS configuration. There are options to override this behaviour if necessary.
Native Windows containers don’t do this. Docker for Windows will resolve container names from the Swarm and will then use the default external DNS (Google DNS on 8.8.8.8) to resolve external addresses. It will not use the host machine DNS settings nor can its behaviour be overridden with the --dns flag. This is a serious problem if your container depends on services within a private / corporate network.
This appears to be an issue with the Docker Windows images (nanoserver / windowservercore) rather than with the engine. Microsoft might get round to fixing it but given its half-hearted support for Docker, it might not.