The default domain IP ranges used by Google APIs and services are allocated dynamically and change often. To get an accurate list, refer to these two lists that Google publishes and updates frequently:
- IP ranges that Google makes available to users on the internet
- Global and regional external IP address ranges for customers' Google Cloud resources
To obtain the net list of default domain IP ranges, subtract the ranges in the second list from the ranges in the first list.
For a Python script that will automate this process, see IP addresses for default domains.