Uploaded June 2026 | Updated September 2026, 23 minutes ago

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One of the most common TCP analysis flags in Wireshark is TCP Dup ACK (Duplicate Acknowledgement). But what does it actually mean?

In this WCA tip, we examine duplicate ACKs, why they occur, and what they may indicate about network performance.

Download the pcap and follow along:
github.com/packetpioneer/youtube/blob/main/tcp-duplicate-acks-chrisgreer.pcapng

You'll learn:

• What a duplicate ACK is
• Why TCP sends duplicate acknowledgements
• How Wireshark identifies Dup ACKs
• When duplicate ACKs may indicate packet loss

This video supports the Wireshark Certified Analyst (WCA) exam objectives and helps build practical packet analysis skills.

🎓 Learn more with the Wireshark Certified Analyst (WCA) course:
packetschool.teachable.com

WCA Objectives:
wireshark.org/pdf/wca-objectives.pdf

#Wireshark #TCP #NetworkAnalysis #PacketAnalysis #WCA #Networking