A GIS administrator team must perform system maintenance over the weekend. The team must ensure that members do not add, publish, or edit any items in ArcGIS Enterprise. Members still need the ability to access and view items as necessary. Which action should the team perform?

Placing ArcGIS Enterprise in read-only mode is the designated administrative procedure for system maintenance scenarios. This mode specifically prevents all members from creating, modifying, or deleting content, services, users, and groups. Crucially, it maintains view-only access, allowing members to continue accessing and viewing items, which directly fulfills all requirements of the maintenance task. This is a single, system-wide setting designed for this exact purpose, ensuring a controlled state during maintenance without causing a full service outage.

B. Change members' user role to Viewer: This is an impractical and inefficient method. It would require manually changing every user's role and then reverting it, risking errors and overlooking accounts.
C. Clone the organization's content to a standby deployment: This describes a high-availability or disaster recovery strategy. It is not a standard procedure for planned maintenance on the primary system.
D. Disable ArcGIS Web Adaptor: Disabling the Web Adaptor would make the portal and its services completely inaccessible to all users, violating the requirement to allow viewing of items.

1. Esri ArcGIS Enterprise Documentation. "Set portal to read-only mode." ArcGIS Enterprise 11.0 Documentation, Administer > Portal for ArcGIS. This document explicitly states, "When in read-only mode, users can still view content on the portal website, but they cannot create, update, or delete content... This is useful for many administrative workflows, such as performing data migration, upgrading the portal, or patching the operating system..." This directly supports option A.

2. Esri ArcGIS Enterprise Documentation. "User types, roles, and privileges." ArcGIS Enterprise 11.0 Documentation, Administer > Portal for ArcGIS. This source details the capabilities of different roles. While it confirms a Viewer role is read-only, it illustrates that changing roles is a user management task, not a system maintenance mode function, making option B an incorrect approach.

3. Esri ArcGIS Enterprise Documentation. "About ArcGIS Web Adaptor." ArcGIS Enterprise 11.0 Documentation, Install and configure > ArcGIS Web Adaptor. This document explains that the Web Adaptor is the entry point for requests. Disabling it would block all access, which contradicts the scenario's requirements and invalidates option D.