A network administrator is troubleshooting an application issue after a firewall change. The administrator has confirmed that the port and protocol are accessible to the user, but the application is…

ifconfig (or ip addr) is used to display and configure network interface parameters like IP addresses and MAC addresses, not to capture or analyze network traffic content.

tcpdump is a powerful command-line packet sniffing tool that captures and displays network packets. It allows an administrator to analyze packet headers and payloads, providing detailed insight into communication at various OSI layers, including the application layer, to diagnose application-specific issues.

nslookup is a command-line tool used for querying the Domain Name System (DNS) to obtain domain name or IP address mapping information, not for inspecting application layer traffic.

traceroute maps the route a packet takes to reach a destination, showing the IP addresses of intermediate routers, but it does not provide insight into the application layer content of the traffic.