What initial capability should you activate in Microsoft Defender for Endpoint to manage IP addresses and URLs?

The initial capability you should activate in Microsoft Defender for Endpoint to manage IP addresses and URLs is the feature that allows for the creation of custom network indicators. Custom network indicators enable security teams to define specific IP addresses or URLs that are considered malicious or trusted, thereby proactively managing threats associated with network traffic. By utilizing this feature, organizations can enhance their ability to detect and respond to potential threats that utilize specific network paths, improving incident response times and overall security posture.

This capability is foundational as it helps establish a tailored security environment that reflects the unique requirements and threats faced by an organization. It not only allows for the identification of malicious activity but also aids in refining detection rules and enhancing visibility into network communications.

The other options, while valuable, serve different functions within the Microsoft Defender ecosystem. For example, endpoint detection and response (EDR) in block mode focuses on actively blocking detected threats, but it is not specifically geared towards managing network indicators. Live response for servers provides real-time access to endpoints for investigation and remediation but does not specifically address network management. Web content filtering deals with monitoring and controlling web traffic based on content but does not directly involve managing specific IP addresses and URLs as custom network indicators do.