All ARDC DOIs must be associated with a resolvable URL pointing to a landing page for the data being identified. This means that resolving ARDC DOIs is as simple as prefixing the DOI with the DOI System's resolution service address (https://doi.org/) in a browser address bar e.g. https://doi.org/10.1594/PANGAEA.726855.
Note that as of July 2018 DataCite is no longer registering test DOIs in the global Handle System. This means that test DOIs will no longer be resolvable. The main reason for this change is to prevent handles being orphaned after the test DOIs are deleted.
It is important to understand that the Handle System (the technical infrastructure for DOIs) is a distributed network system. The consequence of this is inherent latency. DOIs have TTL (time to live) defaulted to 24 hours, so any changes will be visible to the resolution infrastructure only when the TTL expires.