1. Setup Nuget remote to a different Artifactory instance which is offline.
2. Setup Nuget remote on your instance.
3. Setup Nuget virtual on your instance with the above 2 repos included and place the Nuget from the 2nd instance first for resolution.
4. Perform nuget install of a package not in the cache.
You will get a not found error as Artifactory will not proceed to the 2nd repo when he can't find the package in the 1st repo.
Reproduced with Nuget client 220.127.116.11