Which of the following software allows a network administrator to inspect the protocol header in order to troubleshoot network issues?

A URL filter is a content-filtering tool that blocks access to websites based on URL categories and does not inspect raw protocol headers.

A spam filter analyzes email content to identify and block unwanted messages and is unrelated to protocol header inspection.

A packet sniffer (such as Wireshark or tcpdump) captures network traffic and decodes protocol headers at each layer, allowing a network administrator to inspect fields like source/destination IP, TCP flags, port numbers, and application-layer data. This detailed visibility into protocol headers is essential for diagnosing connectivity issues, misconfigurations, and performance problems on a network.

A switch is a Layer 2 network device that forwards frames between ports and does not provide protocol header inspection or troubleshooting visibility.