Hi everyone,
We've run into inconsistent behavior when federating ArcGIS Server with Portal for ArcGIS, and I'd like to get some input from the community.
Our standard approach:
- Services URL: we use the URL configured through the Web Adaptor, matching the DNS name registered for the environment.
- Administration URL: as a first choice, we try to use the machine name (or FQDN, when available) on port 6443

The issue:
In some installations, using the machine name (or FQDN) for the Administration URL doesn't work correctly, and we're forced to fall back to using the same DNS name we use for the Services URL (just on port 6443) instead. Interestingly, this happens even on single-machine deployments, where we wouldn't necessarily expect name resolution or certificate issues to come into play. We've seen this behavior recur across multiple versions (11.0 through 12.1), not tied to one specific release.
Is there a recommended best practice for choosing between machine name/FQDN and DNS name for the Administration URL during federation?
What typically causes the machine name/FQDN approach to fail — could this be related to wildcard certificate SAN/CN matching, internal DNS resolution, or hosts file configuration? We use wildcard SSL certificates in PFX format across all our installations
Any insights, best practices, or documentation pointers would be greatly appreciated. Thanks in advance!