In IQ Server, there is a list of repository names and a repository manager column showing an opaque ID value. The ID may look similar to this:
In the case where there are multiple repository manager instances using the same IQ Server and similar repository names, determining which Nexus Repository instance is being referred may be unknown.
The repository ID shown in IQ Server is the node-id value in Nexus Repository 3.
You can get the node-id from a repository manager REST resource when authenticating as an administrator user:
Nexus Repository 3.8.0 and newer: http://localhost:8081/service/rest/atlas/system-information
Nexus Repository 3.0.0 to 3.7.1: http://localhost:8081/service/siesta/atlas/system-information
curl -u admin:admin123 http://localhost:8081/service/rest/atlas/system-information -s | jq | grep node-id
There is also a UI showing this value and a button to download the JSON in the UI as well under Administration -> Support -> System information.