For a rapid connectivity check, AOS-CX tcpdump is the most efficient diagnostic method because the administrator only needs to establish whether the expected connection request is followed by a server response. AOS-CX provides diag utilities tcpdump specifically for packet-level troubleshooting and supports filters for source/destination IP addresses, source/destination ports, protocol, packet count, and verbosity. This permits the engineer to isolate the client-server conversation and observe the exchange directly from the switch CLI in real time. Aruba Networks

For example, the capture can be constrained to the server IP or application port so that TCP SYN/SYN-ACK behavior, resets, or other responses are immediately apparent. Where transit data-plane traffic must be redirected internally, AOS-CX supports CPU mirroring in conjunction with its diagnostic capture facilities. Aruba Networks

The other choices are valid techniques for different requirements but introduce additional work. ERSPAN is preferable for remote full-packet analysis , a destination-port mirror requires a physically attached capture device, and TShark-to-PCAP is appropriate when a persistent capture must subsequently be examined or transferred. For the stated objective— quickly confirming whether the server responds —real-time tcpdump inspection is the appropriate choice.

Study Guide References: AOS-CX Monitoring; Mirroring; diag utilities tcpdump; Packet Filtering; Troubleshooting Client-to-Server Connectivity.

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