Blocking a subdomain of a website from being indexed

how can i prevent a subdomain to not s开发者_开发问答how up in search results. like it.domain.com

Is there an htaccess file??

Put a robots.txt into its root directory and have it say

User-agent: *
Disallow: /

decent spiders (i.e. all big search engines) will respect it.

I'm not sure but Try this::

User-agent: *
Disallow: /

NOTE :this code is already submitted