An orange cloud means that your web traffic will pass through the CloudFlare system making your site Faster, Safer and Smarter. A gray cloud means that your traffic will not pass through the CloudFlare system.
The CloudFlare network is designed to proxy web traffic, if a subdomain serves a purpose other than web traffic it shouldn't be used with CloudFlare. Please note the use of SSL certificates requires a paid account purchased through CloudFlare directly. The following subdomains should be marked with a gray cloud to prevent issues:
- calendar
- cpanel
- csv
- dns# (regardless of number)
- exchange
- direct
- git
- imap
- irc
- local
- localhost
- mobilemail
- mx
- ns# (regardless of number)
- panel
- repo
- secure
- sftp
- sites
- smtp
- ssh
- ssl
- svn
- webmail
- webstats
If you have a question regarding what subdomains should or shouldn't be used with CloudFlare please contact support, or consult the official list here.