mediumMultiple Choice
PT0-002 Practice Question: A penetration tester is performing internal…
A penetration tester is performing internal reconnaissance from a compromised host and wants to map the local network without sending any packets. Which technique is most suitable?
⚠ Common exam trap
It's easy for candidates to assume 'passive' techniques like tcpdump still require sending packets, or they confuse passive capture with active scanning methods like ARP sweeps or DNS queries, which inherently generate network traffic.
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
✓
Use tcpdump to passively capture and analyze broadcast traffic.
Tcpdump can passively capture broadcast traffic (e.g., ARP, NetBIOS, mDNS) without sending any packets. This allows the tester to map active hosts and services on the local network by listening to existing network chatter, fulfilling the 'no packets sent' constraint.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use tcpdump to passively capture and analyze broadcast traffic.
Why this is correct
Passive capture with tcpdump places the NIC in promiscuous mode and records Layer 2 broadcast frames such as ARP Requests/Replies, DHCP Discover/Offer handles, and NetBIOS/mDNS announcements. Since the tester sends zero packets, this approach avoids triggering IDS/IPS signatures, ARP watch tools, or host-based alerts, while still revealing live hosts, MAC-to-IP bindings, and potential host roles from routine broadcast chatter.
- ✗
Send ARP requests to all possible IP addresses using a ping sweep.
Why it's wrong here
An ARP-based ping sweep (e.g., arp-scan or manual ARP requests) actively transmits a crafted ARP request to every possible IP on the subnet. These frames are visible to network monitoring tools, can be logged by switch port security or NAC solutions, and generate replies from every live host, creating a detectable burst of broadcast traffic that defeats the passive requirement for stealth.
- ✗
Query the local DNS server for all host records in the domain.
Why it's wrong here
Querying the local DNS server, especially attempting a zone transfer or using enumeration tools, is an active interaction that the DNS server will log. Even if the server misconfigurations allow a full zone transfer, the records only cover hosts with registered A/PTR entries, missing DHCP-assigned coffee-shop printers, unregistered workstations, or temporary lab VMs, so this method leaks both your intent and incomplete intel.
- ✗
Use traceroute to discover network paths.
Why it's wrong here
Traceroute functions by actively emitting packets with incrementing Time-to-Live values so that intermediate routers respond with ICMP Time Exceeded messages. This creates a distinctive and easily correlated traffic profile, is frequently logged by perimeter and core network devices, and primarily maps network paths rather than host presence, making it unsuitable for quiet internal host discovery.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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