We generate certificates that are intended to be used for server authentication in a couple of places:

- `bin/elasticsearch-certutil http` command  ( See `CertGenUtils.generateSignedCertificate` in `HttpCertificateCommand` )
- TLS auto-configuraion for node startup ( see [`AutoConfigureNode`](https://github.com/elastic/elasticsearch/blob/814f7f9f52cb8c05db6465b9bfc818ea5d76c575/x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/AutoConfigureNode.java#L454) )

In these cases we know that the certificate is meant to be used for server authentication, so we can set Extended Key Usage extension to `1.3.6.1.5.5.7.3.1`
x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/HttpCertificateCommand.java
nodeDescription = certName;
        }
        printHeader("Which hostnames will be used to connect to " + nodeDescription + "?", terminal);
        terminal.println("These hostnames will be added as \"DNS\" names in the \"Subject Alternative Name\"");
        terminal.println("(SAN) field in your certificate.");
        terminal.println("");
        terminal.println("You should list every hostname and variant that people will use to connect to");
        terminal.println("your cluster over http.");
        terminal.println("Do not list IP addresses here, you will be asked to enter them later.");
        terminal.println("");
        terminal.println("If you wish to use a wildcard certificate (for example *.es.example.com) you");
        terminal.println("can enter that here.");
        final List<String> dnsNames = new ArrayList<>();
        while (true) {
            terminal.println("");
            terminal.println("Enter all the hostnames that you need, one per line.");
            terminal.println("When you are done, press <ENTER> once more to move on to the next step.");
            terminal.println("");
            dnsNames.addAll(readMultiLineInput(terminal, this::validateHostname));
            if (dnsNames.isEmpty()) {
                terminal.println(Terminal.Verbosity.SILENT, "You did not enter any hostnames.");
                terminal.println("Clients are likely to encounter TLS hostname verification errors if they");
                terminal.println("connect to your cluster using a DNS name.");
            } else {
                terminal.println(Terminal.Verbosity.SILENT, "You entered the following hostnames.");
                terminal.println(Terminal.Verbosity.SILENT, "");
                dnsNames.forEach(s -> terminal.println(Terminal.Verbosity.SILENT, " - " + s));
            }
            terminal.println("");
            if (terminal.promptYesNo("Is this correct", true)) {