NSX-T has a default API rate limit of 100 requests per second, per client. This limit is sometimes already triggered when you are using the GUI with multiple people using the admin account. If you are using the API to get status information or configure your platform, you very likely know the error. When you exceed the limit, the following message is displayed.
Client 'admin' exceeded request rate of 100 per second.
This article shows a couple of methods to mitigate the limit.