Last Updated on June 24, 2026
About COS Service Devices (COS‑SD)
A COS Service Device (COS‑SD) is a component of Central Office Services that provides local test content hosting and content management for a COS Configuration. Using a COS‑SD improves test security and performance by keeping testing activity on the local network.
This page focuses on the COS Service Device itself, including its purpose, capabilities, supported platforms, system requirements, and operational considerations.
Why Use a COS Service Device?
Using a COS‑SD helps ensure a secure and reliable testing environment. Because the Testing Devices and the COS‑SD must be on the same network, testing cannot occur off‑network. Hosting test content closer to students also reduces external network traffic and helps provide a more consistent testing experience, especially for tests that include audio, images, or video.
New to COS? If you are looking for an overview of how COS components work together and how testing flows during a test session, start with Central Office Services (COS): System Overview.
COS – SD System Requirements
For details regarding COS – SD system requirements and the number of concurrent testers, refer to the latest version of DRC INSIGHT System Requirements.
COS – SDs and the Number of Students Testing
As a general guideline, the COS – SD software can support a large number of testers who are testing at the same time (concurrently). This guideline is based on the following assumptions:
- The COS – SD is configured for Content Management and Content Hosting.
- The COS – SD software is installed on a dedicated device.
- The COS – SD and network meet the necessary system requirements.
The number of COS – SDs required may differ based on the actual hardware and software specifications of the COS – SD, the network speed, and the COS – SD options selected.
Software Installation and Update Rights
Certain software rights are required to install and update DRC INSIGHT and the COS – SD software depending upon the type of operating system you are using. DRC INSIGHT requires Administrator rights to install it. The COS – SD software requires Administrator rights to install it.
For any changes to software installation and update rights, see COS Installation.
Basic Tasks
The following is a short list of some basic COS tasks you may want to perform and a link to further information.
Task: Use the COS Dashboard to monitor your COS Configurations, COS – SDs, and Testing Devices
Reference: The COS Dashboard
Task: Create a Pool of COS – SDs
Reference: Creating COS – SD Pools
Task: Configure DRC INSIGHT to allow student testing without using a COS – SD (for an extremely low number of testers)
Reference: Creating COS Configurations