Sub-domains on CloudFlare are marked with an orange cloud. Sub-domains not on CloudFlare are marked with a gray cloud.
The CloudFlare network can only proxy web traffic over port 80 and 443. The following sub-domains should be marked with a gray cloud to prevent performance issues:
mail and webmail
nameservers (NS1, NS2)
secure* (unless you enable CloudFlare SSL)
View the full list of sub-domains here: