Which display filter shows only TCP traffic on port 80?

• A. tcp.port == 80
• B. tcp.port = 80
• C. tcp.port eq 80
• D. tcp_port == 80

Answer: (A)

The filter uses a port field tied to the TCP protocol and an equality check. Using tcp.port == 80 selects packets where either the source or destination TCP port is 80, and since the tcp.port field applies to TCP traffic, this shows only TCP traffic on that port. The other options use invalid syntax or field names: a single equals sign is not the correct operator; eq is not the standard form in this context; and tcp_port uses an incorrect field name (the correct field uses a dot, not an underscore).