hardMultiple ChoiceObjective-mapped
200-201 Practice Question: An analyst is investigating a potential data…
An analyst is investigating a potential data exfiltration. The logs show a series of DNS queries with subdomains that appear to be base64-encoded strings. Which technique is likely being used?
⚠ Common exam trap
Cisco often tests the distinction between DNS tunneling (data exfiltration via subdomain encoding) and DNS amplification (a volumetric DDoS attack), so candidates must recognize that base64-encoded subdomains point to tunneling, not amplification.
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
✓
DNS tunneling
DNS tunneling encodes data (e.g., exfiltrated files) into subdomains of DNS queries, which are then sent to a malicious authoritative DNS server controlled by the attacker. The base64-encoded subdomains in the logs are a classic indicator of this technique, as the attacker uses the DNS protocol to bypass network security controls and covertly transmit data.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
DNS tunneling
Why this is correct
DNS tunneling encapsulates data in DNS queries to exfiltrate information.
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DNS amplification
Why it's wrong here
DNS amplification is a DDoS technique, not exfiltration.
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Fast flux
Why it's wrong here
Fast flux rapidly changes IP addresses, not encoding.
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Domain generation algorithm
Why it's wrong here
DGA creates random domain names, not encoding data.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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