Finding the URL names for Test/UAT/DEV environments

We just added a new Sales Cloud environment to our stable - and Ive been asked to admin this somewhat hidden CX Sales product (5 user) testing site.

My company has asked me to add users to the TEST environment.

I can login to production and work normally, but no one seems to know the URL for test.

I tried what I thought was going to work by adding TEST into the URL- which works for our very large live environment, but no go with this new little one... here is the example: https://fa-xxxxsaasfaTEST.fa.ocs.oraclecloud.com/

Anyone have a fool-proof way of adding their lower environment names to the production URL to get a good URL? (We have DEV/DEV2/TEST/UAT) and PROD.