When a predefined interface map is modified in the Juniper Apstra global catalog, two key things occur. First, this change does not retroactively affect blueprints that have already imported that map. Blueprints maintain their own local catalog, which contains a copy of the interface map as it existed at the time of import. Second, modifying predefined, vendor-supplied elements is not a supported practice. During a software upgrade, the Apstra system will overwrite any user modifications to these predefined elements with the new default versions included in the upgrade package to ensure system integrity and compatibility.

C. Changes made to predefined interface maps can have a significant negative impact, potentially causing unpredictable behavior or failures during software upgrades.

D. Anomalies are generated based on a mismatch between a blueprint's intent and the operational state. A change in the global catalog does not alter a blueprint's intent.

1. Juniper Apstra 4.2 User Guide, "Design" Section: The guide explains that design elements like Interface Maps are stored in a global catalog and can be imported into a blueprint's local catalog. This architecture implies that once imported, the blueprint's version is independent of the global source. (This concept is fundamental to Apstra's blueprint architecture).

2. Juniper Apstra 4.2 Installation and Upgrade Guide, "Upgrading Apstra Controller" Section: Under the "Important" notes for upgrading, the documentation explicitly states: "Modifying predefined elements (for example, rack types, templates, device profiles) is not supported. If you have modified predefined elements, they will be overwritten during the upgrade process." This directly supports the statement that changes are discarded upon upgrade.