MongoDB's MMS public IP addresses are changing due to a network migration from AWS Classic networking to VPC networking, which will impact customers using DNS TTL overrides, hard-coded IP addresses, or firewalls controlling outbound access. The change is scheduled for January 29, 2015, and workarounds include updating firewalls, DNS servers, and applications to use DNS instead of hard-coded IP addresses. Customers can file a ticket in JIRA for assistance with implementing these changes.