The Customer Data Hub can send data to external systems via connector actions. Those external systems might restrict access to only an approved list of IP addresses, also called a whitelist.
To allow the Customer Data Hub to send data to your network, add all of the following IP addresses to your whitelist:
US-West-1 - San Jose, California
US-East-1 - Ashburn, Virginia
EU-West-1 - Dublin, Ireland
EU-Central-1 - Frankfurt, Germany
AP-Northeast-1 - Tokyo, Japan
AP-Southeast-2 - Sydney, Australia