As I know about useful of telnet <webhost> 80 for troubleshooting. But some case It's useful for hacker to grather information from your server such as your version of apache, version of OS and etc. As I , however, known you can minimize result of those detail (ServerTokens Prod).
This is my question : How to hide the result of detail from my server? Neither telnet via port 80 or any method.
PS. In case of apache configuration