200-201 Network Intrusion Analysis Practice Question
An analyst is investigating a PCAP file and wants to reconstruct a conversation between two hosts. Which Wireshark filter would be most appropriate to follow the entire TCP stream?
⚠ Common exam trap
200-201 often tests Wireshark filter syntax and the difference between filtering by IP, protocol, and stream. Candidates might choose 'ip.addr' thinking it shows a conversation, but it includes all traffic to/from that IP, not just one TCP stream.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
tcp.stream eq 0
The filter 'tcp.stream eq 0' is used in Wireshark to follow a specific TCP stream. When you right-click on a packet and select 'Follow TCP Stream', Wireshark automatically applies this filter with the appropriate stream index. This filter displays all packets belonging to that particular TCP conversation, allowing the analyst to reconstruct the entire session between the two hosts. Other filters like 'ip.addr' show all traffic to/from an IP, which may include multiple streams, and 'http.request' only shows HTTP requests, not the full stream.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
tcp.stream eq 0
Why this is correct
`tcp.stream eq 0` isolates every packet belonging to stream index 0, letting Wireshark reassemble the full bidirectional conversation regardless of ports or IP addresses. This satisfies the stem's requirement to follow the entire TCP stream, since stream indexing groups related segments that Follow TCP Stream also relies on.
- ✗
dns.qry.name
Why it's wrong here
dns.qry.name matches DNS query names only, so it displays name-resolution lookups rather than the TCP payload carrying the conversation. It is tempting because DNS filtering is the correct approach when investigating domain-generation-algorithm malware or tunnelling, but reconstructing an established TCP stream needs the Follow TCP Stream function.
- ✗
ip.addr == 10.0.0.1
Why it's wrong here
Filtering by a single IP address captures every packet involving that host, including separate connections to other peers, so it cannot isolate one conversation. It is tempting because host filters are the standard way to scope traffic to a suspect machine during triage, which is a legitimate task, but reconstructing a specific TCP stream requires the Follow TCP Stream function.
- ✗
http.request
Why it's wrong here
http.request matches only HTTP request packets, omitting responses and any non-HTTP traffic in the same connection, so the exchange cannot be reassembled. It is tempting because this filter is the right choice when isolating outbound web requests during an incident, but following a complete TCP stream requires the Follow TCP Stream function.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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