Remarkety syncs your data by accessing a web service on your platform. This web service is either built-in (on Shopify and PrestaShop for example), or exposed by one of our plugins. Remarkety will make a request for new data every couple hours in order to keep your store info up to date.
Some servers and web firewalls might block these API requests, so you might want to add our IP's to your firewall's whitelist.
The complete list of Remarkety IP's is found here.