To better answer this question, we must first explain how IP addresses work on the Grid. Due to the architecture of the Grid, incoming and outgoing connections will function differently.
By default, your Grid is supplied 1 IP address to be used for all of your domains on the service. This IP address is also shared with other customers on the same cluster. You can find this IP address listed in the DNS section of your Server Guide. While this is the IP address for your Grid, any requests for your domain(s) received from any of the IP addresses on your cluster will complete successfully, allowing your domains to display. The only reason that this IP address should change is if it is performed manually by one of our engineers. This is sometimes done for maintenance purposes, but it is very rare. Exact reasons for such a change can vary. In the event that we do need to change your IP, you will receive a notification with details.
As the Grid is a clustered hosting solution, it is made up of many different servers to better handle load and increase performance. Any outgoing connections from your service may be sent from any of the servers associated with your particular cluster. This means there is currently no way to have a dedicated IP address for outgoing connections or to know in advance which specific IP the connection will originate from.
Can I have a dedicated IP address for my Grid?
Dedicated IP addresses are not available on the Grid. Dedicated IPs are no longer needed on the Grid to use an SSL certificate, thanks to the implementation of SNI.
What if I require whitelisting of the outgoing IP address of my Grid?
As this IP address can vary, you will need to whitelist the entire IP range for your cluster. To locate the cluster upon which your service resides, please read: How to find your Cluster and Storage Segment.
This information may change at anytime. Please open a support request if you need the latest list.
What if my IP does change while using a third-party for DNS?
Any requests for your domains that is received from any of the IP addresses on your cluster will complete successfully. Your services will function should a change occur. Again, such a change is very rare.