What is the primary function of a network sniffer in troubleshooting?

The primary function of a network sniffer is to capture and analyze network packets. This tool allows network professionals to observe and diagnose network traffic in real time. By capturing packets as they traverse the network, a sniffer provides insight into the data being sent and received, including various protocols and communication between devices. This information is invaluable during troubleshooting, as it enables the identification of issues such as packet loss, latency, or misconfigured settings.

The ability to analyze the contents of the packets can reveal problems related to application performance or network configurations, allowing for precise measures to be taken to resolve issues.

The other choices reflect different network-related tasks that do not align with the primary function of a sniffer. Blocking unauthorized access pertains to network security measures rather than analysis. Configuring network devices involves setting up hardware or software settings, while optimizing data transfer speeds is focused on performance enhancements rather than dissecting the data flow itself. Therefore, capturing and analyzing network packets is at the core of what a network sniffer does, making this choice the standout answer.